As the title says, why there's a need to be stopped just because of the decline? if you've been with the market and you have sold even before the bull run, you should feel nothing on this matter because it's just another normal correction that really has to happen after a great bull run.
Every decline is a new signal for buying. Don't invest your lifesavings, don't open big leverages in futures trading
That's the dumbest thing anyone can do even if the investment opportunity is definitely on the successful side of things. Also, trying to go for an all in with leverages is stupid because that's basically gambling.
It is a gamble and the newbies are likely to get that feeling of doing and taking risks as if they can manage the risk too easily for them. I've seen several newbies who have done that and regretted what they've done.