You make an account called john. He posts, does well for a few months, and earns himself $1,200 steem power. That helps him get around. Everytime he makes a new post, he upvotes himself, and instead of it going $0.01 he's now showing $0.10 now. People have bookmarked his page and he's popular.

john one day wakes up and starts thinking "hey! I could use my steempower of $1,200 in a collusion group vote". Things go well for the next month, and he gets $1,400 of steem power. A few whale bots start to realize john isn't writing stories anymore, he's part of a newly identified vote selling business.

Everytime the john account votes now. A whale bot comes behind him and downvotes whatever he voted on. Effectively ruining the power of john's vote. The vote group kicks out john seeing this. john's account is now tainted. That $1,400 he earned in steempower is now worthless for upvoting purposes. He decides to power down the $1,400, and start a new account on a new name that the bot no longer knows about. He starts off with $10 steem power and has to start all over again.

Yes, he doesn't lose his $1,400. But what he does lose, is the effectiveness of the steem power itself, if he abuses it and a whalebot contradicts his votes.