In my opinion the biggest mistake you are making is watching newbies on youtube who pretend to be "experts". Such videos may get you some basic ideas but they are terrible for decision making. You have to watch the market itself and most importantly look at the charts. Just zoom out and see how each altcoin has been performing over the past years (not just couple of weeks or months). That gives you a better view on whether bag-holding altcoins is a good idea or now...
Well said those YouTubers can be deceiving all just for the views and hype of the projects sponsoring them underground, and one of my most information sources for altcoins is Bitcointalk and other cryptocurrency communities where members share their Personal experience and knowledge and also help out with real-time analysis, so good for the ops to already stick to his present portfolio and better still increase some of his potential assets holdings like Bitcoin XRP Ethereum and the rest of those known assets if he have enough cash reserves.