Big altcoins in top 20 ranks don't need BTC dominance that much unlike those micro cap altcoins, once BTC starts appreciating in value top altcoins will do the same, this is why it's better to build your crypto bags with a few top altcoins instead of those micro cap that many refer to as hidden gem all in the name of making insane gains.
No pain no gain. that actually depends with how much money that owned by you. If you have lots of money and investing in the top 20 is possible caused your capital will determine how much profit you can gained it from the market. if you are only a small trades and investing in the big cap token just like a dumb people who dreaming investing 100 and got 1000000. Big coins are good only for those big chunk investors.