I think for new investors this is something natural, even old investors often experience it. Doubt is something that is natural in bitcoin investment because investing in bitcoin is much different from other investments such as gold or land. therefore if you want to invest in bitcoin you need a strong mentality and can control emotions well.
I have also been in that position, at that time I was very hesitant to buy because I was afraid the price would continue to fall. finally I decided to participate in the airdrop and bounty first while studying bitcoin price movements. over time my doubts slowly disappeared after I understood the movement of the bitcoin price that the longer the bitcoin price would continue to rise. to clear doubts before investing in bitcoin try to understand bitcoin price movements first and use the unused money for investment.