But if you hold Bitcoin in your own wallet where you have the keys and control all the transactions that go on in it, is more secure to hold Bitcoin at the moment.
Do you mean bitcoin is the safest and most reliable option at the moment? you're right but that doesn't mean all altcoins aren't worth holding because as you can see most altcoins have bottomed out and it's time to accumulate for the next bull season. eth, ada...also bad coins? if you dare to say they are coins not worth investing in, then I bet you that eth or ada will bring profits many times greater than bitcoin in the next bull season. there are also a lot of altcoins worth investing in, mate.
The first coin most investors are looking at is of course BTC and currently the market is uncertain in its direction and many are waiting for positive news in this case. 7 proposals are currently waiting for the deadline for approval of the Bitcoin Spot ETF by the SEC, around mid-October.
I am also a fan of ETH and it is also a good investment and has strong fundamentals as well as being the king of Altcoins. BTW, I think it's a good idea if you want to invest in just two, or if it's more convenient, we can choose one of the two and if held and maintained it will be very profitable, especially in the next bullish season as you said above.