IMO, lifetime bans should be replaced with something like 90-days ban. This much duration is enough to make someone realise the mistake!
Honestly if you try find difference between real life prison & lifetime ban from forum than you have to understand the result of punishment first.
In real life people get punishment for a period of time. Where he signs a lot of agreements during his bail. Thats why if he commit any further crime in future will get more punishment according to his agreement.
But in forum if anyone did the same thing twice you have nothing to do. Because its not possible to take legal actions against him. So its the best choice to give anyone lifetime ban. Otherwise there's always a chance for another scam.