It is not an impossible thing to make a living out of participation in bounty campaigns, it is a possibility alright. But yes it needs a lot of work and I think a 100 a week is an overkill. Well maybe that friend of yours must have had a good paying work at present to promote that huge a number per week.
Going back, I know one that have quit his job and now participates full time in bounty campaigns.
I just wish him well though.