Trading Against USD instead of BTC or ETH

So I've traded a bunch with BTC, first back in 2013/2014, and then again this year, and recently ETH as well. So far I've been successful trading ETH, but I always end up losing a lot of BTC when I trade against alts. I'll sometimes have good runs and make good money but altcoins always crash at some point and leave me with huge losses.

So I just started thinking, why not just trade BTC against USD instead. I've already invested a bunch of money in BTC and ETH, and while it would be nice to make my losses back from trading altcoins (and I am still trading a little bit with altcoins) I think I'm gonna try out trading against USD.

It's all about perspective.
When you trade to make more BTC, well first of all you're trading two moving targets, and one of those moving targets (altcoins) can crash down a lot at any time. It can be highly profitable, but also very easy to lose a ton of money, as has always in the end happened to me. BTC/USD means you're just trading one moving thing against the stable dollar.

Now this is where it gets interesting. I know Bitcoin is always going to go up. Sometimes it may take just a few minutes, sometimes if you buy in at a bad time it will take a long time, but at some point in the future it will always be higher (at least these days in crypto while Bitcoin is still a small market). So you are guaranteed at some point to make a profit on every single trade, its just a matter of timing it right so it you buy just before it goes up and not just before it goes down for a while.
Now, the goal is not to make more Bitcoin but to make more USD. That's what makes each bet a sure thing for success. So with BTC/USD trading the goal is to maximize profits. Whereas trading to make more BTC (using altcoins or even just using USD) is highly risky because altcoins can basically crash at any time and BTC is always trending up against USD. When trying to make more BTC the goal is not to maximize profits but to minimize losses/risk. This is because it is so risky if you try to maximize profits you will lose money, so you want profits but to minimize the risk of losses.

If you're just trying to make more USD, then it doesn't matter when you buy bitcoin in general. You buy, wait for it to go up, sell, hope it goes down so you can get an even better deal on the next buy, but even if the price goes up thats okay because you're not trying to get more bitcoin, just more USD, so you can still buy back higher and just sell against when it is higher again. Literally there is no risk here! Its just about how much you can maximize your winning. And having only ever lost BTC with trading altcoins, trading with 100% success guaranteed to make more USD sounds like a pretty great thing!