Is Material Wealth Bad?

Arth (earning money), is one of the purushartha (something everyone should aspire for), so earning money is not something looked down in Hinduism, but rather encouraged.

Having said that, Brahmins (People who are adviser, philosophers, teachers etc), are not allowed to accumulate more than they need, as money would otherwise compromise their ability to provide ‘fair and just’ advice. But, in return to that, they would get immense respect from everyone in society. Please note we are talking about Brahmin as a Varna, and not people born in Brahmin families (more details: Varna System)

For others, while there is no restriction on how much they can earn, but given that Moksha (self-realization, liberation) is also a something they should aspire for, the money they earn must not create un-necessary karma, which mean they should earn by appropriate means, and spend them on things, which will help them to get towards Moksha.