Of course, there is no garuantee that your wallet can withstand the number of losses needed to recouperate your loss.
Place £1 starting bid on number 3
£2 bid on number 3
£4 bid on number three
£4x2= £8 gained
£1+£2+£4= £7 lost
Total win is your startign bet.
OK? now go try this on your friends and see how much you can win from them.