Hello
after 12 years i remember i bought bitcoin in 2010
is it possible to sell more than 50,000 bitcoins at once or is it better to sell direct to a private individual like grayscale or microstrategy?
Well, Congratulations if it's true your a billionaire now but we doubt that

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It is possible to sell that amount of bitcoin there was really no limit as long as there were volume in the market you could sell it off, the problem was your cant sell it all at once since its a high volume your gonna need to finds a high volume market for that but if there is one you could easily sell it off. We rarely see orders in over 1-4 bitcoins, most of them are lower than 1 bitcoin. Also, you might experience some issues especially in cashing out because some might have limits in it. It's better to sell it in percentage it's already a huge amount of money but bitcoin is still a good investment so through the years you could probably sell 5 BTC and then 10 in the coming years.