My advice is spend more time and money on improving your salary potential. Straightforward stuff like getting professional certs, learning more about your industry, network, know what your colleagues are doing.
Money not just for courses, but join events and even cater some budget for coffee chats. I used network using linkedin, find someone interesting and invite them for coffee/lunch.
Then do spend some time, even without money, on your personal development; like health and fitness, side hobbies. Many of my model managers and executives still look sharp at their 40s/50s, with interesting hobbies too.

So the goal is to upgrade your image, so people will perceive you as a potential managerial material. Of course, your work performance must be solid. And naturally, people will want you in higher positions, and higher pay will follow. No need to chase for it.

IMO, that's a better use of time than focusing on investments and side hustles.
And it did work well for me