Bubble games are pure ponzis and therefore will, at some point ALWAYS fail.
You join it, and need people to join below you.
Out of the money you spend in joining, admin takes their cut, and the rest is spent in trying to give the person at the top of the list the amount of money they are due.
EG
Bubble offers 120%
Admin fees 10%
You pay $1
Someone joins for $1, 10 cents go to admin, 90 cents go to your payout, but you are owed $1.20, so you are still 30 cents short.
So someone else must join in order for you to be paid.
Now 2 people are waiting to be paid. This needs new people to join so they are paid.
Eventually all bubbles will die because they can't keep getting new members. If you want to ensure you make your money back + interest then only join when they are new - and even then thats no guarantee.
I avoid such ponzis at all costs.
Ponzi = not good news, especially in the medium term.