I, on the other hand, replace my phone every 3 years. I literally put $20 aside every month for three years towards my "phone budget" then take that money at the 36th month and buy whatever best phone I can get at that price.
I adopt the same budgeting approach towards buying my consoles too lol.
My previous phone I paid $120 for and lasted me two years, my current phone I paid about $150 and has so far lasted me 3 years. So I guess I could put $4.50 a month away to fund my phones. xD
Predictions (Made July 2019)
LTD: PS4 - 130m, Switch - 110m, XBO - 52m 2019 : PS4 - 15m, Switch - 18.8m, XBO - 4.8m 2020: Switch - 22m (Peak Year)