You don't move BTC around, I usually convert to Litecoin to transfer. Bitcoin is kinda like a grandpa at this point. Plus, $20 is a drop in the bucket when you're talking about cryptos. Although malakaix has a good point, that another year of this sort of profit is unlikely, this year was crazy. I mean other than when bitcoin shot up crazy style, people aren't making loads of money on bitcoin. People are mostly making money on the altcoins. I mean my friend's first investment beyond BTC/ethereum was Raiblocks/XRB, he bought a lot of it at 20 cents per coin... it went up past $20 per coin in a little over a month. That's 100 times his investment. At that point, a $20 transfer fee means almost nothing. Of course, he didn't transfer with bitcoin I'm sure.
On exchanges, you trade coins for other coins for a very small exchange fee, it's usually around 0.2% of the total amount. On exchanges you're not transferring coins between wallets, it's all happening on the excahnge, so the Bitcoin fees don't apply when you're trading it, only when you're moving it out of exchanges or between private wallets.
Malakaix, I feel like there is certainly some amount of uncertainty involved when picking cryptos to invest in. But by reading as muhc as you can, you can start to get a pretty good idea of which projects are not just hype and are actually producing something of value. The infrastructure coins are good bets (like ethereum except of course ethereum has already skyrocketed - though it's almost certain to continue to grow so is a good long-term investment). Also there are areas that blockchain is moving into in technology, and identifying the top few contenders in each area is also a pretty good bet. That's basically what I'm doing.