I am thinking about how this will affect adoption. If only 0.1% own 40% of BTC, then how will this affect adoption? Is Bitcoin less likely to take off if we have such giant whales? The market will always be susceptible to manipulation if there is such extreme unequal distribution.
OK, let's put it in a slightly different way: In 2009, 100% of bitcoins were owned by just one person. Today, nobody knows (the often-touted figure of 0.1% owning 40-50-60% is wrong, because it doesn't account for one address holding BTC from multiple owners, like an exchange, or multiple addresses holding the BTC of just one owner, like me, you and everyone else). However, it is safe to say that today 100% of all bitcoins aren't owned by one person. I know that because I own some, and people I know own others.
Now, is this likely to get better distributed or less so?
Bitcoin is scarce. There only exist a certain amount at any given time, and there will never be more than 21 million. Yet, the number of people who own bitcoins, as evidenced for example by the number of active wallets, is growing all the time.
The only way for the distribution to get worse would be if those who own bitcoins never spend, and simply buy more, until they own them all.
This is clearly absurd, as a bitcoin that isn't spent and never will be spent by definition is pretty much worthless, so there wouldn't be much point in hoarding them in that way.
Ergo, the distribution will tend in the other direction, crucially as the market becomes more liquid in the coming years.