I have invested BTC way back 2015 and hold it for a very long time until I sold it last December 2017 for about 18,000$ 
That is the power of long-term investment, holding coins is my bread and butter when it comes to crytocurrency world.
Wow you really slay it, it's so nice to invest in Bitcoin as an early bird. And now, you are financially stable, holding for a long term basis is more appropriate with stable financial status, thus making it more profitable because you are not in a hurry to sell off some coins when you are in need. That is the power of long-term investment, holding coins is my bread and butter when it comes to crytocurrency world.I have a business here in Philippines, and 30% of my profits monthly are alloted for investments in cryptocurrency. Right now, I am holding differents coins whice are BTC, ETC, LTC, EOS and Ripple, I see this potential coins or altcoins that could bring huge profit margin in the future. I chose them because of their potential growth, sustainability, security and profitability. You have to do research before getting into something that's involve with money in order for you to avoid lost, I suggest that you peak at least TOP 20 coins in the market today in order to have peace of mind, just avoid coins that do not have solid support from the community and developers.
Indeed, researching is the most important aspect in terms of investing especially in cryptocurrency, because of such high liquidity in the market. You can lose and also gain a lot. Me too, I am currently planning to invest for a long term with these top 20 altcoin when I have my capital.