It’s a great advantage that you are actually thinking to invest in bitcoin with your funds on hand. However, the fact that it’s highly volatile, then never invest all in, or never stick for bitcoin as your only investment. If you are aiming to make secured profits, invest also in other investments like real estate or stocks as they can also be profitable too if you know how these investments work.
wait, what you said in this case about real estate or stocks is indeed very good but back to the current context he OP is studying and he earns BDT 7000 / month or when we look at the current exchange rate of $65.22 / month and even then it must be deducted around BDT 6000 / $55 for OP's family needs and personal needs so that only about BDT 1000 in this case the rest he has.
Even though the advice you said is quite good, when it comes to Real Estate it is still very far in my opinion especially when we know that the conditions in being in Real Estate besides requiring a very large capital, it will also definitely take longer for the income results, not to mention the maintenance which makes this a little less appropriate.
I think there is no problem with what can be done first even though it is as you said that bitcoin fluctuates and there is no certain guarantee here, but on the other hand I think it is still very feasible if you really want to be in bitcoin.