Bitcoin is probably the best investment you can make today, and probably one of the few coins that will still be around in 10 years time. Bitcoin still has a long way to go, so just keep on buying and holding.
Bitcoin is the most popular cryptocurrency out there, and this is very important for mass adoption and price movement. As more people get into crypto, they will start by looking at BTC. Meaning a more likely chance of them buying some over any other coin.