In conclusion, 76 out of 132 validators holding 95% of total LUNA staked. So that means 57.5% validators holding most of the LUNA and the top 10 validators holding around 41%. To me, that seems a little bit concentrated but LUNA users are free to choose and redelegate their token without any lock period.

So, from the tables below, we can see that these 76 addresses holding around 353,087,646 LUNA.

As of writing this, there are 370,524,047 LUNA token being staked in all available validators. To answer the bounty's question on how many validators hold 95% of LUNA, we have to state that 95% of total staked LUNA is 351,997,845.

Table below shows the current top 10 validators by their voting power and voting power = amount of LUNA token delegated to them.