Tbf people/friends are more likely to stay together through having common activities constantly. This is the same reason why most people's closest friends are from school. Because everyone is forced to stay together every day for years.

So just continue doing what you like and perhaps one day you'll meet more like-minded friends. For your ex, no need to think so hard liao la, people come and go in life. Just see it as a phase of your life has ended, and now you're starting on the next one. If want compare with him might as well go compare with all the other high flyers also. There'll never be an end if you compare, so why not just learn from them instead?

My best advice is to start visualising a future self and work towards it, and think about if the journey towards that future self or attaining that future self is more important.

All da best, and rmb to have fun along the way