The best way to earn bitcoins is by working a day job and converting your fiat into bitcoin.
Other than that, it requires you to have money to invest in things to buy and sell.
Investments and gambling are surefire ways to get rid of all your bitcoins.
which is basically investing your time, many are not doing it, because they want to get bitcoin without touching their fiat, seeing how they want to dump in fiat after they buy bitcoin, and they are not willing to wait for the pump, hence they want an easy way to acquire bitcoin...
but i would add to not invest more than 10% of your income, per month, you obviously need it for something else in real life
with let's say, $1k per month, you can buy almost 1/2 bitcoin per months, should be enough