It's not always so simple to interpret that just because you see someone powering down.

I'm not currently a witness but for the most part I always have a power down active. That does not mean I actually take the Steem out and sell it. Sometimes I end up powering it back up, or I am simultaneously powering up more than I am powering down (for example, this week I powered up around 200K STEEM, but I still have power down running as usual).