Because I want the option of putting it on my github and showing potential employers who also use React that this is what I do in my spare time, because they like to believe that

Hedging bets by simply being consistent and staying relevant

Not the OP but I use React for all my small projects. I do it because it’s the right tool for the job. Why is it the right tool? Because I seems 40 hours a week working with mammoth React projects and therefore its the tool I can “just be productive” in. When working in side projects it’s critical for me to maximize time spent working on the business logic rather than reading documentation on some new tool and googling new error messages to figure out what I didn’t glue together correctly.