I saw many authors take this way.
I’m interested, because I want to discover all Envato can offer but I don’t want to lose other marketplace income.
(Yes, I’m not a millionaire, by the way :D)
I’d like to have opinions! Do you think it works or it may be a loss of time?
Thanks in advance! 
Sure it works out, but it really depends what you are selling and if you want to make Envato the exclusive seller. Although the percentage is much less I know a lot of authors have found this very beneficial especially in stock photography due to the big competition out there.
It’s all down to you and you will only be the decision on that one, not me, not others, not Envato, but you - good luck and I wish you the best of success 
We should be able to set our own prices (but never price lower than the average price) on a non-exclusive account. Selling your work elsewhere for a higher price is pointless if the same item can be found here for a lower price.
Personally, my sales here on AJ vary too much. Spreading your item across marketplaces is IMO a much safer way to get a steady income.