That's right, people do make mistakes themselves and then hope for the place to fix it. I have seen this in exchanges a lot, people end up sending stuff on the wrong chain, and hope that they could get it back. Technically speaking if the exchange (or casinos) check it, they could find the money, but it's not their job to hop on network to network to find your money and credit you, check to see if it's spent and 99% of the time it's not even touched.
Cryptocurrency transactions are irreversible so if you make mistake, you lose your coins. Sometimes, you can get support if make mistake in deposit but usually you don't get that support. Some platforms can support you, but very rarely and even they provide support, they charge you support fee. The support fee is expensive so if you make mistake with a small money, just forget it and move forward. Learn your lesson and avoid it in future.
So long story short, it is your responsibility and you should be aware of what you are doing. Been in crypto for many years, and I have never sent a single transaction to anywhere wrong before in my entire life.
It is because you are carefully by your checking and it is because you have good habit on the Internet. That help your devices are clean and not infected by hazardous things.