You must not have visited his witness post, here is a link so you can get a better idea of what the requirements to become a witness are as well as @yunkzilla reasoning for why he wants to be a witness.
Here is an in depth post by @pfunk :
https://steemit.com/steemit-guides/@pfunk/a-full-steemit-user-s-guide-to-steem-witnesses
And here is @yunkzilla's witness post so you can get a better idea about "who" he is:
Have a blessed day.