Somewhere along the line, tech students got the idea that the key to success is to have many side projects and side hustles going at once. While it is true that in very narrow, specific cases something like a GitHub project could fill in gaps in a resume, it's rare that companies even look at GitHub work as the deciding factor in a hiring decision. It's too easy to let your energy, attention, and motivation get diluted across too many side projects. The problem is amplified when people start entering relationships and eventually having kids, further diluting their limited time and energy.
Some of the worst offenders are things that don't necessarily feel like a side hustle but nevertheless drain inordinate amounts of time. Daytrading stocks and cryptocurrencies commonly traps people into constantly checking their phone, Twitter, and portfolio to avoid losing money or missing out on breaking news. The pocket change most people make (or lose) on day trading is lost in the noise relative to a successful tech career.
The best advice I have for career success is to pick one thing at a time and focus intently on it. Use your off time to do anything else: Social activities, physical activities, or even simply relax and recharge for the next day.
It's better to do one thing well (usually your job) rather accumulate a lot of half-finished side projects or side hustles that are constantly stealing attention.