A bookie doesn't work like that
Stake * odds = winnings return, not stake + (stake*odds) = winning return
I use the vbexperience plugin and the stake is always count x2, as i mention, for a winning bet.
For example :
A member has 13 points for participation
He makes a winning bet : 8 points @ 4.00 = 32 points and another loosing one 2 points @ 2.00
Why this member has a total of 42 points ?