Hmm, well people will not be spending their bitcoins recklessly. If they do spend it so for e.g. on a house or in another company, they still hold the power, with the underlying value of that power being bitcoin. The only real spending that would occur would be on depreciating assets, which would only account for a small amount of the purchases made. The rest would be hoarded in appreciating assets, so they never lose control of the power they first received with the massive wealth disparity that may come from bitcoin.
You make a good point, however there are counterpoints to this.
1. Whether wealth is held in stable currency or an appreciating asset,
the wealthy owner isn't consuming resources just by ownership. However, luxurious living
requires spending actual wealth and buying depreciating assets.
And with Bitcoin, once the coins are spent, they are gone. This is in sharp contrast to the
current system where the rich get richer. So it may start out as more skewed, but over time,
Bitcoin actually favors more equitable wealth distribution, and the trend is in the right direction.
Right now, we are on the wrong track, with power and wealth getting more centralized.
With Bitcoin, it would forever march toward equality. In the long run, all wealth would be earned.
2. Also, even appreciating assets require real wealth to be spent on their use as a resource.
A house requires property taxes to be paid. A classic car requires maintenance, etc. These
things require further distribution of funds.
3. Yes people will convert Bitcoins to other assets as you say, but this will not happen
all at once, in say 40 years. it will happen in various stages along the way...each time,
further distributing the wealth.
4. There may be some generational stashes of coin, but they would erode over time
when used for luxury, and would only cause occasional disruption.