Do you believe the FBI holds the biggest number of bitcoin?
How would we know? How certain are they? We can't tell because nobody/no one would say how many bitcoins he/she has on his/her hands

I do believe that government do really have some decent amounts of Bitcoin on their hands.Remembering on the site that they have seized back in the past on which they do have confiscated or make hold of those bitcoins and im sure until now they do have the power or the holdings of those coins. Government wont just be blind on bitcoins progress and they would definitely go with the flow as long theres money involved on it.
Governments are not innovators they only redistribute the money, so they charge taxes and then they pay someone to do something for them, that is they way it works, If bitcoin begins to challenge their power I think they are going to take the easiest approach they are going to join the crypto market and each one of the governments of the world are going to issue their own crypto.
Things are getting worst than worse with government and bitcoins. If anything like that happens, we will again get stuck in the same place where we are right now. They will be controlling our money, we will have to pay taxes, everything will remain the same except the fact that then it will be just in digital form. Kill me before that day, please!