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.
The altcoin market is more of a gamble than an investment like bitcoin but not all of us are useless, and I agree with you, ETH is an altcoin that we should consider adding to our portfolio mine. Not only in the short term but in the long term, I also believe that in price, ETH will not be able to surpass BTC, but it can give us better returns if we compare from now on. This will displease many bitcoin maximalists, but we have to admit it, and the risk of ETH will still be greater than bitcoin.