We lead off, of course, with Elly and John's self-willed ignorance of how their children actually live. When you watch them get outraged because they think they're being generous, it's sort of obvious that they labour under the laughable misapprehension that while the prices of what they want to buy have steadily risen over the years, the price of chips, candy, pop and funny books hasn't changed since 1965. Well, that and the fact that were they to become aware of said change, they'd bleat about the unfairness of it all before banning the children from buying such things.
This is, of course, because Mike, Lizzie and April constantly needed to reminded that their allowances weren't really their own to spend any more than their belongings were theirs to dispose of as they saw fit. For some ungodly reason, John and Elly seem to think that they have more of a right to decide what the kids spent their money on than they did. Given that I get the same queasy feeling remembering John hectoring Mike about spending all his money on someone else (because of John and Elly's unswerving belief that the knowledge that he gave up on buying foolish things that are foolish because his parents cannot use them to make his poor parents who sacrifice so much happy is the best and only benefit Mike should derive out of life) that I get remembering him AND Elly reminding Mike that since they do him the FAVOR of letting him live in their house, he owes them favors back, it comes from thinking that their idiotic belief that despite their parents having lived through the depression of the 1930s and the Second World War, THEY lived lives of true privation because they had to wait more than five seconds to get something they wanted.
Given their inability to even conceive of a world in which the prices of things they don't buy are dragged upward like everything else and their belief that their kids are slackers because they falsely remember themselves as being overtaxed, it's rather easy to see why they pulled that annoying stunt with the roller skates. Instead of simply cracking open their wallets, they lectured Mike about the importance of money and hard work. Once he'd realized it would take forever to get what he wanted out of THEM, he ended up learning that he had to work around them to get stuff he wanted.
This sort of thing can't help but give Mike and the other kids an unhealthy relationship with money. Had the strip progressed along a logical, natural line, we would have seen Michael emulate Weed. We could see him sink a crap-load of money into forbidden items and proscribed foods only to have him become a more or less responsible figure once he'd realized that he was on his own. Given what a deluded egomaniac Elly is, it's not hard to see that she'd take credit for teaching him how to handle money responsibly. It's like how she'd take credit for teaching him how to cook and clean for himself despite sabotaging him in those areas too.