I appreciate all your effort to help me and clarify me question that keep bugging my head.
About fees , there are fees to buy BTC or Ether , sell them for Eur/USd and even transfer them to a wallet right ?
The user above has already answered the question but if your goal is to eliminate as many fees as possible then going with P2P platforms might be best.
You should use something that has free transfers, like Wise or Revolut. Add to that the free escrow fees that Binance and some other providers have... you will then end up only paying withdrawal fees.