Those who invested in bitcoin way back 2009 had not experienced any bull run before nor have much knowledge about the blockchain technology, yet they took the risk to invest. You and I have witnessed a bull run and heard about the numerous potentials of crypto so why do we still have to feel reluctant to invest in bitcoin. Let's be optimistic about our digital assets because its all we have.
Do you think those people who invested in 2009 doesn't have any knowledge about it?? If you are investing into a coin which is new what will you do?? Will you do some research about it and learn about it. I agree with what @avikz said that those people who invested last 2017 are less knowledgable about Bitcoin compare to those who invested last 2009. They just invested because of profit and not for the technology.