Some sidewalks are designed for bikes, especially in Europe. If you are on one of those, pedestrians beware (especially in Netherlands and Germany).

I prefer bike lanes on roads or bike trails. Driving on roads with traffic for a small amount of time: OK, but all the time: hard no.

I've stopped advising people to not ride bikes on sidewalks, especially opposite the direction of traffic, even in situations where it's legally permitted (for example, kids in my area are allowed to ride on sidewalks).

People get really worked up when you ask them to stop, really angry! Which I find so odd because if somebody comes up to me and says something is both illegal and unsafe, I check the laws, and put some critical thought into what the risks could be, and then typically comply if I'm convinced, or simply respond with "I have heard what you are asking, but it's not absolutely required, so I will continue to do so."

There are few to no pedestrians because there are few to no sidewalks. Where sidewalks exist, it is legal to bike on them in my state.