The answer is simple as this, BTC is not as profitable the way altcoins are, when you invest in BTC, the highest profit you can get that will no exceed 1x, but altcoins that have low market cap can do 10x, 20x, 30x and this is why you see lot of people still buy altcoin and when it comes to trading too, altcoins-USD is more profitable than BTC-USD but altcoins have high risk, if anything goes wrong with altcoins, you will regret buying them. My little advice for you is that if you buy BTC on coinbase, withdraw it to an external wallet, don't leave your coin in coinbase exchange because if anything goes wrong, you will lose acess to your BTC.
Bitcoin will not exceed x1? Did you mean x10?
But in any case, it will be a reliable investment, for which you will have to worry much less than for altcoins, because of which you can lose your investment. Also, you can't be sure if an altcoin will give you x10 or x20, it can also only do x2, or not grow at all, if it were that easy, everyone could buy altcoins now and become rich in the future, but it doesn't work like that.