Some are holding and working on writing a new BIP or are in the core code. Some don't have the technical background and just want the coin to improve itself.

Honestly I wouldn't want every 'rich' person committing code to the repo but that is just me.

What are some things that one can do to improve bitcoin? here's what I can think of:
  donate to the foundation
  create a node, improve the network
  be active in the community