Generally you should do what:
- Maximizes your personal well-being (though note I'm not saying "wealth", because they two are not always the same), and
- Satisfies your personal and ideological principles as well as possible, at least to the point where you can live with yourself.
Just because we have systemic critiques doesn't mean we should go live in a cave and eat bugs. To the degree possible we should prefigure the society we want to build, but torturing ourselves individually to do it is both unproductive and likely takes away from our focus on more important things like organizing and taking direct action that impacts the system. We do tend to make personal sacrifices to further our ideological goals, but there's both a practical limit and one where we shouldn't be cruel to each other in our expectations.
Many of us are vegans. Most of us probably avoid buying shares in oil companies. But all of our circumstances are different. Perhaps people salting Chevron to radicalize union organizing there will wind up with its stocks in their retirement accounts that are difficult to divest from without harming their ability to retire, due to their particular circumstances. It seems pretty shitty to expect someone to just get rid of them without us having some kind of dependable (e.g. mutual aid) infrastructure in place to take care of each other in our old age.
Poor people can't afford to lend money when they're struggling just to eat and make rent. It's not a viable way for them to "keep up" with inflation.
But in a sense you're right: inflation (by itself) isn't the problem. The problem is that wages don't keep up with it. Because the labor movement has been failing not only to make gains, but to prevent failures (e.g. keep our effective wages from going down). Most forms of capitalist passive income keep up with inflation by design, which is no accident.