Most of the owners of those others coins come up with things that are too good to be true to attract people to invest in them, and it pays off cause that's why many people still buy Alts and shitcoins out of ignorance all in the name making profits in the future, though some are out of greed too cause they're aware of the consequences but are willing to take chances despite knowing they could lose everything
Perhaps the ideas that are attached to those shitties (shitcoins) are merely the so called Flaws of bitcoin which are obviously not true but some how and for some reason they succeeded with ideas of solving a none existing problem of bitcoin by coping it's protocol and creating a useless coin out of it just to satisfy the curiousity of some folks who do not believe in themselves so they couldn't believe in an original coin/cryptocurrency (Bitcoin). Most of the shitcoins claim to solve one or more issues but in reality they are more or less scams intended to rob the some folks who are probably ignorant of this intentions.
Hence anyone who knows the truth behind this coins and proceeds to buy them are either risking the lowest risk (fiat) into a higher risk that is probably not going to profit them anything but for belonging sake they would want to feel among by going into risk lossing the lower risk the had (fiat). Perhaps I consider fiat a risk for the fact that it depreciates over a long term while the higher risk is the shitcoins which could depreciate 99% in less than 24/hrs.
Over the years, Bitcoin has shown that it has the ability to reach different ATH and it would still set another in the near future, which makes it the best Cryptocurrency for investment, that alone should discourage people from buying other coins for investment purpose but then that's where ignorance and greed comes in like I said earlier. Well, another thing is lack of patience some of those investors are not willing to wait for long-term cause they want to make quick profit, they disregard the major benefits of the future and chase after quick profit that seems very risky, forgetting or not knowing that Bitcoin investment got strategies that helps counter the risk of loss and that's why it's completely different from others.
Perhaps bitcoin has not just become the top #1 cryptocurrency for the mere sake of reaching all this ATH but it has become the top #1 because it's a paradigm and every other coins came into existence because bitcoin existed. it has become the highest cryptocurrency for all of its characteristics even though some folks seems to create propose problems that are none existing into it for a mere purpose of taking chances from other individuals who are not knowledgeable of reality. Perhaps it's also true that there is nothing perfect but bitcoin in its original form has its purpose served and still serving and will always serve it's purpose.