My real world experience, comparing my 2014 Focus Cayo w/ SRAM Rival (bought used for CAD2k at My Little Bike Shop on College St) vs my box fresh Cervelo Aspero w/ GRX600 (equivalent to Shimano 105):

Old frame versus new frame I don't really feel the difference. Adjusted for the rolling resistance, I can't tell you that the 2020 bike is faster, more responsive or anything different than the 2014 bike.

Component wise, yeah, the shifting is better with newer components, but not game-changing better.

Verdict: all things being equal, I wouldn't hesitate to buy a used bike over new, and at $2,300, you probably can't lose. Ride it for a year, and if you want something newer, sell it for what you've paid. Unless you're super serious, I don't know you'd be able to tell an 8 year old bike with upgraded components over brand new.