Skill before or after university education will depend on some factors. The type of skill you want to learn (Online or Offline) and the level of financial support for your higher school education. It also depends on your region or country. In some countries students receive financial support from the government while in some countries, no government support. There's also a high level of unemployment even after university in some countries. In this case, your skill will save you because you can work independently.

If you don't have reliable financial support but want to attend university, then learning the skill before university might be good for you so that you can support yourself financially when you finally gain admission into the university. But if it is an online skill, you can still learn while in university.

I will use myself as a case study. I learned Diesel Injection Pump And Injection Nozzle maintenance (Offline Skill) before entering university for my higher education. Currently I'm already in my 3rd year in the university courtesy of the money I make from my acquired skill. Learning a skill is a good decision regardless.

I work independently and still work for my boss (Trainer), especially during the holidays. My next skill will be in WEB3. You too can do it.