Activities List for College Applications - "pay to play" activities should be minimized or avoided?

My kids’ DC trip cost maybe $200. They took the train, volunteered, stayed in a hostel. (And this was a private hs.) Same with service trips. One $135, the other close, both through a local church, real work.

This brings up the mention that those kids going on expensive international trips often have nothing, nada, zip in their communities or even the US , where they work with local needs. (Some random hour here or there or donating a coat aren’t the same.)

How many enrichment programs does a kid truly need before these become an avocation in themselves?