Predatory loans were maligned as "usury" long before "rent-seeking" or Scary Marxists came along. For good reason. They're bad for society and the economy writ large.

Classing all loans as usury help Europe back for a long time.

I guess you could class some rent as predatory as well, allowing others to use your property for a fee is not necessarily predatory (unless you're of "property is theft" kind).

Investment is generally considered profit-seeking behavior (i.e. not rent-seeking). Building an apartment and renting it out is clearly profit-seeking behavior, but if you were continuing to rent it out doing the bare minimum to keep it from falling over 40 years later, that would be pretty clearly rent-seeking.

From this, we can conclude that there must be some point after an investment is made where continuing to benefit from it transitions to rent-seeking behavior.

Would holding some stock 40 year after buying it for dividend also be rent-seeking?

Would rebuilding the apartment every so often straighten you back to profit-seeking?

Rent-seeking is just a meaningless insult if framed like that, it highlights no economically net-negative behaviour.