You are correct about them caring more about money than anything else. They probably care about some rights but padding their pocket is king.
But they aren't a front for gun manufacturers. They don't care about them either. Gun manufacturers aren't large donors to the NRA. The NRA only cares about their own profits. Gun sales don't really help them that much. Depending on the liberal source in a 10 year time frame 2005-2015 I believe donations from organizations was in the 20-53 million estimated range. Even if it's 53 million, that is insignificant. In just membership dues alone that's less than half of what they take in yearly.
https://www.businessinsider.com/gun-industry-funds-nra-2013-1
This site is agreeing with what you are saying but it's wrong. Just wanted to give you a sauce for the 20-53 and 10 year.
Also they include groups like midway, brownells, etc which are citizens making that donation through programs like round up a buck on the purchase of an item. So it isn't even the site using their profits, it's just the middle man for private donation.