As a matter of fact, Bitcoin can not decrease global poverty because poverty depends on many factors. Bitcoin alone is not enough to elevate the socio-economic level of the people. Yes, it can help people with their earnings to an extent, but for that, the person should have some amount of savings to start investing. For example, if we talk about less fortunate countries where the daily wages are below 10$, how can one expect an investment into BTC from them?
I am of the opinion that only a privileged few from those countries will be able to invest in Bitcoin.
DCA is a very good option, as you suggested. This way, it will not burden the individual, and he will have some investment for the future. But, for that, the person should be earning more than his needs.