**1. Introduction**

Since 2020, we have faced drastic changes in our lives due to the pandemic. This caused a big paradigm shift in working styles. Parallel careers or multiple jobs are getting more common, and people are ascertaining their own competencies. The utilization of personal knowledge will continue to accelerate and this study sheds light on its societal value.

Aoki [1] revealed that participation in knowledge sharing has a significant positive impact on contributors' well-being. Those findings are more pertinent as utilization of personal knowledge increases under the ongoing paradigm shift in work style, and the expansion of C-to-C business. However, the reason for the correlation between knowledge sharing and well-being has not been identified. This research aims to reveal the relationship between knowledge sharing and well-being.

Due to the growing sharing economy and the large ongoing paradigm shift in work styles caused by the pandemic, people have more opportunities to utilize their personal knowledge than ever before. However, vast amounts of personal knowledge are untapped. For instance, one instantiation of personal knowledge is user innovation, and user innovation research has pointed out the 'market failure' in its diffusion due to a lack of incentives for the innovators [2, 3]. This study contributes to increase knowledge sharing and filling the gap between personal knowledge and society.

#### **1.1 User innovation and social welfare**

Since von Hippel [4] pointed out that not only manufacturers but also 'users' innovate, user innovation has been studied by various researchers throughout the world. In early research, the term 'users' referred to firms that were supplied products by manufacturers; in other words, user innovation was carried out in the business-to-business community. Over the decades, the importance of individual consumers as user innovators has been articulated (e.g. [5]). In this digital era, the line between a firm and a consumer is becoming blurred, and co-creation between the two has become pervasive.

Some users innovate by themselves and whose innovations occasionally have been commercially successful. Previous studies showed that user innovations increased social welfare because user innovators created financial value from their leisure-time activities [6, 7]. Furthermore, user innovation is distinct from producer innovation in that the former provides benefits from participation, including the use or sale of the output to the innovators themselves [6, 8]. Consequently, user innovation which brings satisfaction to the innovators increases social welfare better than producer innovation.

#### **1.2 Diffusion of user innovation**

Even if it has a high potential to enhance social welfare, user innovation tends to be restricted to innovators themselves and not diffused. User innovators are likely to choose free information diffusion, rather than paid diffusion, and avoid seeking commercialization on their own or through an existing firm, because it costs more than they would gain. Earlier studies have shown 'market failure' in user innovation diffusion [2, 3]. When valuable innovation remains underground, it is society's loss.

Each user innovation is based on personal needs, which, by nature, are selfcentered. Thus, innovation communities play an important role in integrating these isolated individuals [5]. Baldwin et al. [9] revealed that user innovators who commercialized their innovations had participated in innovation communities at an earlier stage and improved their ideas. Earlier research has shown that user communities play an important role in diffusing user innovations and has examined the innovators' motivations to participate in these communities.

People tend to join peer communities (e.g., open-source software communities) to fulfill personal needs. Then, their participation becomes a hobby, and they discover that they are helping other people [10]. In addition to personal needs, feedback from peers and enjoyment were found to be important motivations [11–14]. Feedback in the user community also plays a key role in increasing entrepreneurship [10, 15].

#### **1.3 Knowledge sharing and well-being**

Diffusion of user innovation is ultimate knowledge sharing and contributors enjoy financial and/or non-financial benefits from sharing. Aoki [1] focused on non-financial benefits and revealed that knowledge sharing increases contributors' well-being.

In terms of psychology, Seligman [16] defined well-being as the ultimate objective of positive psychology. He argued that well-being is sustainable and separate from 'happiness' and suggested the importance of flourishing as a standard to measure well-being. Flourishing consists of five elements, positive emotion, engagement, relationship, meaning, accomplishment, or PERMA for short [16]. Each element represents the following.


Aoki [1] visualized non-financial benefits from knowledge sharing with the measurement of PERMA which was developed by Butler and Kern [17] and have been used to explain the relationship between well-being and a continuous process such as career [18], education [19, 20], and hobby [21]. Although this is an important finding, the cause has not yet been revealed. Thus, this research explores why knowledge sharing increases well-being. In line with Aoki [1], this research follows Seligman's definition of well-being and adopts PERMA to examine the changes in well-being that knowledge sharing contributors' experience.
