You made good point, it doesn't matter the kind of coin you hold hence there is a bull run the price will rise.
However, what really needs to be noted is:
That not all altcoins are able to survive and ultimately rise in the bullish era. not all altcoins can be like that even in a bullish era. There are many altcoins that were bullish in the previous era but only stayed at that number and couldn't rise up like other altcoins. This is why you need to be very careful if you want to invest by holding altcoins. because again, not all altcoins can rise up in the bullish era. Meanwhile, if it is Bitcoin, it has a bigger reason to rise up. So, be careful in choosing coins for holding.
What those people do not seem to get is that it is only in hindsight that it is easy to identify which one of the thousands of coins that are created each year will become successful, if you actually try to do this then it will be almost impossible to identify that coin before it skyrockets, so they are conveniently forgetting that for every single altcoin that succeeds there are dozens or even hundreds of coins that fail, and by taking the risk of investing in those coins they may never see their money back, as the coin they picked disappears and never goes through any kind of pump.