These private entities and institutions buying and holding huge amounts of bitcoins are a double-edged sword. For one, they can and they will pump the price up by buying significant amounts of the cryptocurrencies and then holding it, more people will follow them and this will induce price increase. However, the same could also happen when these institutions dump their savings, which could mean imminent death for bitcoin and starvation for us.
if in case they will dump, they should have good reasons why they will do so. because dumping means, they dont believe anymore in this market. or in other scenario, they are manipulating the market just to get as much profit as they can. however, to do that, all these institutions should unite with their movement to make an impact in the market. and that i believe, is hard to achieve. each institution has their own goals why they are investing in crypto, and more then likely, they have their own 'secret' plans how to manage their crypto assets.
definitely, there are risks involved if in the future most bitcoins will be on the hands of these big companies. however, thinking about that, you will just wear yourself for nothing. right now, just take care of your own business and go from there...