That is a bit strange given the fact that 2017 was known not only for a high btc price, but even more insane altcoin prices. ETH at $1k and even something as obscure as Experience Points (XP) had enormous value. About $800 worth of XP today was nearly $5000 back in Jan 2018 which was its peak price.
For me that was quite astounding to see a shitcoin doing so well. There are probably other better examples that I am unaware of.
Most likely this has to do with the fact that at the beginning the coin that you are more likely to buy is bitcoin and for that you need a bitcoin wallet, however once you understand that in this market there are many other coins other than bitcoin then you begin to invest in some of those coins, so even if in 2017 altcoins went up a lot more than bitcoin only a minority of investors decided to invest in them and after the market crashed many gave up on altcoins and are probably only holding bitcoin.
