No you can't go back in time and buy cheap coins. Stop living in the past and regretting opportunities you missed out on. We're here now and this market is still far from mature. Some time ago people considered 1800$ per bitcoin a lot. Now we're approaching 6000$ in just 6 months.
Look at the future and invest wisely.
We are not late, actually we are lucky because we know crypto world and we don't ignore it,and all we need to do is to study and learn to the coin that has a potential, it is not too late as far as we can invest.