Can somebody explain leverage to me?

So, I'm just going to ignore all the condescending comments saying not to do it, it's not for you etc. But go ahead and make them.

I've been playing around with the demo feature on Bitget where you can play at futures with $3000. I've made a few extra hundred so far.

I'm just trying to understand all the features, the things like mark price liquidation price etc, but also just how it works in general.

Just looking for someone who actually understands this stuff to explain a few things to me, namely where and what the risks are.

I watched a tutorial video that said it's safer to use isolated rather than cross at the start. So I'm doing that.

I guess it's been easier lately because things are generally going up, but even so, I kind of can't work out how it can go so badly wrong for people. I don't mean that in an arrogant "I'm so smart" kind of way, I mean I just don't understand the maths.

So let's say I open a long on BTC with $1000 at 20x. I put a stop loss at maybe -5%, so I stand to lose $50 max (I'm not sure if that the case if I'm using leverage, but let me know. Also there was a post on here recently from someone who said that they opened it with only 1x and then increased it later, which makes even less sense tbh). Then when the price increases a bit, say by 7% , I move my stop loss maybe 5% above my entry price, so there's then no risk. Then after that whatever gains made are increased by 20x?

I mean, I just don't see how that can be true, so I think I'm not understanding something. It's like you buy something for $1000 and it goes up by $100 and you say to the exchange, nah but I want 20x the profit, and they say ok. I don't understand where the corresponding risk is. I guess it's something to do with liquidation price, but if the stop loss is set above that point, then how can you ever lose (unless obviously you pick every single trade badly and keep triggering small stop losses).

Or is it that, if I put $1000 on at 20x leverage then I'm only actually trading with $50, but I still stand to lose $1000.

Honestly, I know I probably sound stupid, but i just don't get it.