Mostly the naysayers are people who get scammed over their own stupidity like buying shitcoins, invest in ponzi scheme, paying fee to unlock reward in fake CEX etc and some of them never buy Bitcoin at all.
This is one of the misconception about bitcoin as well. Most people who have no knowledge about cryptocurrency often mistakes bitcoin and cryptocurrency to be the same. They can not differentiate between the two and when they invest in other cryptocurrencies, they see it as bitcoin investment. When they lose the money to failed projects or probably being scammed, they attribute the blame to bitcoin. Ignorance is the primary cause of this misconception and some of them are not ready to seek knowledge and liberate themselves from having such beliefs.
>>They are so many misconceptions about Bitcoin, if I should start mentioning I could end up being bored while typing. The list goes on and on.
I had an argument with a friend just yesterday, who seemingly believes that Bitcoin is being controlled by a single entity and Bitcoin is not secure.
He said a lot to back his claims which although I can't remember his pin points though.
I knew once that he doesn't really know much about Bitcoin so I decided to back out of the argument.
Misconceptions like this are merely caused by lack of education (Bitcoin related) and sometimes education in general.
First of all, you don't need to engage in an argument with people over bitcoin especially if you know you can not win against them due to your limited knowledge about the technology. You might end up doubting yourself if they present better arguments than you with their misleading beliefs. If care is not taken, you might also begin to lose interest in bitcoin. It is good you back out from the argument but it would have been better if you didn't involved yourself in it in the first place.
By the way, can you remember some few things he said about bitcoin being controlled by a single entity? What is the entity controlling bitcoin? And the instances that prove insecurity of Bitcoin as well. The answer to these questions will help to know the right responses you ought to have given him and discredit his misconceptions.