2012 was a long time but what about the years beyond it? Remember, BTC is said to be invented on 2009/2010. These years are when it struggles a lot to build its name. Luckily it find its way up. Fast forward on 2012 again, BTC is a bit known and had some nice value (finally).
Indeed it takes dedication to got this far if they are one of the OG's in BTC investing but other than that, it also needs a good head and feeling. $83k is not a joke amount, especially for just a digital currency, so it make sense on why it takes over a decade for it to reach this high. After a day or two from your post here, BTC just broken another ATH ($93k) and the value of the coin is now around $88k levels
I guess its decision is now final that it will really hit the $100k that many of us are wishing even before. BTC is actually more decentralized before than now, but in the middle of its run or on its peak, I think yeah that CEX are already a big part of it. If I can name one, I will mention Binance, since it was also very popular that time. They are still a top exchange now but a lot of restrictions have been applied on them later on, and that affected them greatly. In the early days, trading was actually simple but I think it's a bit risky, since there is no KYC yet. So KYC isn't worse as many people perceived.
KYC is a no-no for some - but then again, DEXes are there for a reason, though they are not as convenient, and sometimes, they have problems with liquidity and so on.
So overall - BTC all the way up, with or without CEXes, they won't be the catalyst for its growth in the way that the world's events affect it.