Now my question is, is it good for my future that I have sold my altcoins and invested in bitcoins?
Let's say usually, at first, when you're new to this world you buy several altcoins, then you realize many of them are pointless and it's better to focus on BTC, so I would say you made the right choice. The only altcoins I really like are ETH and BNB, those have a great potential and it's worth having some, especially ETH in the short term it may even outperform BTC.