I think it's wrong to tell people not to try certain trading like future etc simply because you had a bad experience of which I think is as a result of your error in judgement and lack of capacity!
The most important skill in cryptocurrency trading and investment generally is the ability to ask the right question and the efficacy of information that you are using for you decisions. If you can get this two right, and you are able to control your emotion, I'll bet you will succeed in your cryptocurrency trading career!
If someone has a bad experience about their trading and then they must give some tips or advice to newbies the right way to prevent loss like what they already experienced. Telling to newbies that do not try in trading cause I have a bad experience about it is a bad Idea. In trading we can not predict the outcome every traders has a chance of earning big profits so every one can try to invest in their money.