It very wrong to ever think bitcoin is unaccessible, everyone can buy bitcoin as you wish. You can also buy bitcoin using the dca method (buying bit by bit) or the lump sum method (in large portion) anyway that is more convenient to you.
And also the aspect of bitcoin is too hard to understand, capital "NO". There is absolutely nothing that after puting your time and commitment that you will not know or understand better. If you make a good research about bitcoin and everything about it you will surely have a perfect understanding on it.
True. As long as we have Bitcoin wallet, we can buy Bitcoin at any time. We can also create an account in CEX, then we will automatically have Bitcoin wallet there. There is no big problem about buying Bitcoin, it can be done every time. However, people will consider the best time to buy Bitcoin, so they can easily get profits. Anyway, DCA is good but we can use any other ways in collecting the Bitcoin.
It is easy to understand Bitcoin if we are serious to learn it. It only becomes difficult when we are no intention to learn it. Many people only think about the profits, they don't think too much about learning.