You can't judge the distribution from this graph. That is only what's lying in bittrex wallets.
I am sure most whales and dolphins have their strats in their desktop wallet. I know I do.

The only thing this graph tells us is that one big dolphin doesn't bother to transfer his 2Mio+ Strats in his desktop wallet.
Would be too risky for me to let it sit on an exchange like bittrex. And it seems he doesn't trade - so why take the risk?
Maybe it's just peanuts to him