I'm currently still using an iPhone 4. It was an upgrade, I was still using 3GS about 2 years ago. I use it to receive calls, SMS, iMessage, Whatsapp, email (with an iCloud account) and record lectures daily. This is my main phone. I don't use Maps and never take selfies (or pretty much any photos), so this phone is sufficient for me.
My iPhone 3GS still works as well, I use it as a second phone. I also still have an iPad 1 for reading in the bathroom, an iMac 2009 with an external SSD for boot up as my desktop, and a MacBook Air 2010 (with internal SSD) which I use daily for school. I also have an iPad 2018 which I bought because I went back to school (need Apple Pencil to study) and I also needed the extra disk space.
Old Macs are quite long lasting. I wanted to upgrade to MacBook Pro 2018 (or 2019) but was very reluctant due to the horror stories about the keyboard
I regretted not buying MB/MBP/MBA 2015... in 2015.
All my gadgets have never been repaired. I have never bought any Apple Care. If I buy an MBP now though, I'll most likely get one.