If you are a normal person with a working life and salary, you should definitely go for the dca method. Like you said, bitcoin can be life changing if you already have a lot of money to invest in bitcoin since bitcoin is just too expensive.
But this should not discourage people from investing in bitcoin. I would rather slowly but constantly invest in bitcoin than dump a huge amount of money into an altcoin I have no guarantee of making profits.
That is to say that based on the current price of Bitcoin, investing on it is not only for the rich, someone that's not very wealthy can also invest in it, all the person just got to do is come up with methods of investment plan, and for some that falls under such category or a person who doesn't tolerate risk, the dca method is not a bad idea cause the salary earner could invest in bits over time regardless of price and still benefit hugely when a massive bull season comes. Well Bitcoin is by far the best asset for invest but their are still some Alts one could invest on in a short-term period and make profits, not all are pump and dumps moreover the growth of Eth has shown that it could be an asset for long-term investment plan and since the dca method is mostly best for long-term plans I think using the dca method for it is not a bad idea if an investor got spare money.