It’s not worth buying an old phone because the new ones don’t have a sim slot. How many times does the average user even switch the SIM cards out of their phone? I have done it once in the last 10 years and am a pretty tech savvy person. I have a 14 pro with esim (because they only have esim) and have no problem with it. I’ve actually been using esim for years as it means the sim can’t be taken out if your phone is stolen.