No matter what they try to do, this character is irredeemable. It is literally impossible to acquire that much wealth without exploiting others. And even if he somehow managed that, if he actually had the best interests of the town at heart, he wouldn't be hoarding it, he would invest it it in the people
And who's to say he's
not investing it in the people? Maybe the bronze statue was made locally, by a begrudging-but-now-richer craftsman? Maybe the goods and materials for his massive mansion were all sourced as locally as possible, with the same going for the manpower for designing and building it? His whole plan is to put to use his immense wealth to bolster the town's defense by purchasing the
very expensive mermaid queen to provide underwater combat training. Said mermaid queen whose capture, I might add, he actually had no hand in (and who was the victim of a slave trade that he seems more than eager to put an end to).
Don't get me wrong: I'm still leaving myself open to the idea that he'll
maybe still turn out to be a sack of shit down the line (though that seems unlikely), but being obscenely wealthy does not automatically make you a bad person. Think of how many OP isekai protags also wind up becoming ridiculously wealthy, through entirely innocent means (granted, that's not very realistic, but it still applies since this story, too, is in a manga setting).
For a real world example, look at Markiplier: He's got
big YouTube money (sure, he's not
Bezos rich, but given that Grize isn't able to just out-bribe this other merchant and use money to do away with the whole slave trade, I doubt he is either), and he's a legitimately good person.
As a final note, it looks like Grize is rich by inheritance, so
however that money was originally earned, it's likely he had little to no hand in it.