Quote Originally Posted by Kraco
Kakuzu isn't very smart, either, so his evaluation of what manner of a bounty is worthwhile is of limited importance. No matter how big those bounties are, they are mere pocket money compared to the kinds of sums he could get from rich folks needing healing or a new heart to live longer. You know, there would be no end of millionaires that would give him half of their wealth if he gave them 20 or 30 more years with a new heart. Instead he wanders around looking for random bounties...
He wanders around because his duties in Akatsuki involve more than just obtaining money. Such as capturing Jinchuuriki.

I don't know how you can say he's not smart either. Unless your basing that purely on the fact that he's not selling his medical abilities. Because they are definitely portraying him as an intelligent villain.

Also, there's the problem with the fact that, he's a wanted criminal, which means anytime a rich person tries to contract him to perform some medical work, it could just be a trap set by shinobi.

At least with bounties, nobody contacts him directly. He just checks posted bounties, kills them, then shows up at a contact point for his reward.