first, it doesn't matter even if you are more interested in altcoins but most of your portfolio should be bitcoin because bitcoin is the most popular crypto and lowest risk investment. related to tokens that are on the ERC20 network has nothing to do with bullishness because what causes high gas fees is not bullish or bearish but the density of transactions on the network.
honestly investing in bitcoin and giving huge share of investment towards bitcoin is not something that you must always follow.
some people have toleration towards the risk higher than other, so they could freely invest in some random altcoin all the wants, though we all know how bitcoin is good for investment some people just want that speculative nature of some altcoins.