You should never expect to get rich through bitcoin or any emerging technology. It is always important to be alert to anything that sounds too good to be true, or is against the fundamentals of economic law.
Bitcoin is a growing area of innovation, and there are opportunities and risks. Even so far, bitcoin has been growing at breakneck speed, but no one can guarantee that it will continue to grow. Any investment in bitcoin's time and resources requires entrepreneurship. There are many ways to make money from bitcoin, such as mining, speculation or new business. All of these methods are competitive and there is no guarantee of profit. Each person should make an appropriate assessment of the costs and risks involved in any such project.
I think people do invest in bitcoin or any other cryptos in the hope to gain financial profit. There has been a lot of cases where simple housewife or an 8 hour regular working employees become a millionare because of bitcoin. There is nothing wrong to hope for greener pasture especially if this is needed to improve our family's welfare. But you are correct that investors must be careful in their investments because as you said it is very unoredictable and the hope might die off in that case. Nevertheless bitcoin has been a very positive tool for many rich people nowadays to achieve what they have right now so it is just natural for people to take this as an inspiration for them to achieve the same.