Because it is very profitable saving method in last days. It grows a huge amounts in a hours and investors are having a good profit at everyday.
Saving is better than speeding but if you are making a comparison of saving and investing. Then I think you must have divided the scene. There should be some saving amount and then on the flip side, you must be investing in some bitcoin or altcoins.
Reason is, saving will only increase the amount of asset you have, but investing will grow it to more asset and you will ultimately be benefited from it.