TQQQ is up more than 100x since 2009.
What is the optimum amount of leveraged long QQQ?
To maximize profits in a bubble, what is the max long one should be?
I am sure many S2007S would say 100x. That is not a serious answer because a -1% move will wipe one out.
There is no such thing as optimal leverage.
Personally I prefer as high leverage as possible perhaps 100X, or better still 1000X or beyond.
some traders prefer to have zero leverage ( my goodness ) !
The brokers / Exchanges decide on the amount of leverage.
The other question is how many lots should you be trading?
You need to refer to your own trade plan which should talk about money management.
Some might trade NQ with 2 minis, some 5 minis, some 10, 50 ...
Obviously, for beginners, start with small quantity. Then increase it
as you become more confident and successful.
It seems that your money management is not in place. Go get it done.