Bitcoin is not a quick and get rich quick scheme, for any one to have benefits from Bitcoin as an investment it will take alot of time with patients and consistence investing, another criticism is that most people always said that Bitcoin will crash some day buti usually let them know that Bitcoin is not a scammed project just like most of other coins, while they will be having negative feeling about Bitcoin others will be taken advantage of Bitcoin, but there is no reason for arguments perhaps Bitcoin is not for everybody and it is not by force for anyone to be convinced about Bitcoin potentials.
Bitcoin has become too big to fail which means for those people thinking that Bitcoin is going to fail, their wish is not going to be fulfilled. One of the biggest criticism of Bitcoin is that Bitcoin is a get rich quick scheme just as you said but if you invest in Bitcoin, you will come to a realization that Bitcoin is far from that. You have to have patience to benefits from investing in Bitcoin, if you do not have patience you are going to miss out on the opportunity to make life changing money. Bitcoin is not very fast because network can get congested at times but Bitcoin is secured and can not be hacked. The criticism of Bitcoin are most times due to the fact that those spreading the information might have been misinform but they do not know because I do not think Bitcoin has any much reason to be afraid of investing.