Bitcoin is still the first on the list. Its never a doubt for investors to choose bitcoin over other crypto currencies.
I think we all agree with your opinion, even sometimes we get delay and high fees in withdraw process, bitcoin still become our priority in every crypto activity. Some people abandon bitcoin and try altcoin because delay and fees but they will split asset and replace it into bitcoin too, so when people say not use bitcoin again that is non sense. All coin change because bitcoin movement, don't deny it but use it.
But then, some altcoins could be someplace to stay and it seems to be profitable by then as the entire market moving upward. In fact, I'm holding it now (ETH and XRP) and I know that these coins will always be in the tail of bitcoin. Despite of negative feedbacks for these two coins but still, I'm not losing my confidence that this could bring me a positive and satisfying result.
Thus, it is to believe that most investors are also considering these coins and think newcomers will do the same. Not only because of its name but because of its market volume that attracting us to give our trust and confidence.
This still doesn't erase the fact that bitcoin is the most prominent cryptocurrency most investors choose from. It cemented itself in the cryptocurrency world, it has a high profitability rate, and it has huge spikes/forks. Making it one of if not the most profitable cryptocurrency there is on the market. Even most of the altcoins in the market are dependent in one way or another to bitcoin's price. If it dumps, they dump too. If it spikes, they spike too. So it is just natural for people to choose the "best" cryotocurrency out there. Without a doubt.
Aside from that, the halving's coming up on may, people are expecting bitcoin's price to spike drastically, if not reach an all-time-high. All the more reasons for them to choose bitcoin over other cryptos.