It has been more than 5 years since the release of GPT-3.
GPT-5 is a marginal, incremental improvement over GPT-4. GPT-4 was a moderate, but not groundbreaking, improvement over GPT-3. So, "something like GPT-5" has existed for longer than the timeline you gave.
Let's pretend the above is false for a moment though, and rewind even further. I still think you're wrong. Would people in 2015 have said "AI that can code at the level of a CS college grad is a lifespan away"? I don't think so, no. I think they would have said "That's at least a decade away", anytime pre-2018. Which, sure, maybe they were a couple years off, but if it seemed like that was a decade away in 2015, well, it's been a decade since 2015.
GPT-5 is a marginal, incremental improvement over GPT-4. GPT-4 was a moderate, but not groundbreaking, improvement over GPT-3. So, "something like GPT-5" has existed for longer than the timeline you gave.
Let's pretend the above is false for a moment though, and rewind even further. I still think you're wrong. Would people in 2015 have said "AI that can code at the level of a CS college grad is a lifespan away"? I don't think so, no. I think they would have said "That's at least a decade away", anytime pre-2018. Which, sure, maybe they were a couple years off, but if it seemed like that was a decade away in 2015, well, it's been a decade since 2015.