Definitely agree with you that it's a complicated issue that can cause conflicting feelings. Obviously, a growing city like Portland has to grow either up or out to accommodate transplants and population growth. I think one of the big reasons you see calls for rent control are due to the fear that there is too much growing up for people's liking - they enjoy the bungalow home style that is a huge section of Portland's housing, and they don't' want to see it turn into a metropolis of condominiums. If you're like me and see condominiums along major thoroughfare roads as not a inherently bad thing because they businesses onto the first flow which increases walkability around neighborhoods, than you're probably more against rent controls. However, if you're very much against gentrification and pushing out poor residents, then you'd be very much a supporter of rent control.

Another area that supports rent control is the idea of "Rent Seeking" which, albeit extremely loosely related to actual rent costs/increases, worries people because they don't see landlords costs increasing anywhere near as fast as their rents and therefore are a very villanous action. Different from your experience in selling a bike because the bike is much less a necessary commodity. A better comparison would be people being mad at a grocery store for increasing costs of food during a health crisis, just because the demand is there. (Still an apples/oranges comparison but you see what i'm getting at.) This Oregon Live article does a really good job of breaking it down as well. Lots to digest about the debate for sure.