Yes, every 2 years i can have a phone for 20€/30€ it doesn't matter which one
nope
contract aren't a "you get a phone for *20€/30€*"
it's like a car leasing
for example, my Nokia 8 (499chf) with a contract was 0chf my contract monthly cost is 59.79chf but only for 24 month in 21 month from today it will cost 39chf, since i will have finished to pay the 499chf (24x20.79~) that my Nokia 8 cost
my Nokia 8 still cost me 499chf (well... that one is totally worth it tho ... ) nonetheless luckily i did wait till april of this year since it went down from 799chf (not that it wasn't worth it at the previous price ... that was still 200/400chf less than the flagship from some other brands and still competing with them)
it's the same as buying a plain silicone case for 39chf in a local store (or online ... pfahaha) or getting one online for 1.34$ on aliexpress
and it's 3D printed
outside of that ... i got a 128gb uSD for a ridiculously low price and decided that 64+0 and 2 SIM wasn't very useful (as i was almost always at 95% full) so then 64+128 is way more comfy