According to techpowerup the 5080 66% faster than a 3080 for 42% more money after 4 years.The 5080 is meh only because its not much better than a 4080S (compared with 3080 to 4080), but from a 3080 to 5080 its nearly a double of performance...
For context the 3080 was 126% faster than a GTX1080 after 4 years for 17% more money.