Bitcoin is not only currently but forever the king of cryptocurrencies. Everyone can make long-term investments on Bitcoin with complete confidence that they will get profits for sure. Because no one trusts any other coin in the crypto world, everyone trusts Bitcoin without hesitation. Bitcoin, on the other hand, cannot be controlled by anyone, it is fully decentralized and therefore can be invested in blindly. Because of these huge benefits, you should invest only in Bitcoin even if you don't invest in other coins
Not all people trust Bitcoin, there are even people who publicly state their distrust on the market of Bitcoin while others straightly states that Bitcoin is some form of a scam. And there are still other people who trust altcoins, in fact some even hold them until their altcoin holdings moon or become worthless.
As the saying goes, not one can please everyone and not one can conquer all the interests of people. I do agree that Bitcoin can be said as the best investment in the cryptocurrency sphere in terms of liquidity and lesser risk but some altcoins had proven themselves over the years. Holding only Bitcoin may make us miss some good altcoins to invest in, so I believe we should have an open mind when it comes to cryptocurrency investment. After all, we all sought for profit when investment is the topic. Just do our own research and keep ourselves updated and most of all invest only what we can afford to lose when dealing with altcoin investment.