Just to be clear, it was $250 to $1,000 per hotspot/AP that they were charging, not per device. (That is, if your convention needs 3 hotspots, presumably you would pay $750 to $3,000, no matter how many people connected.)
Considering a conservative estimate of $1000/week for a single year across a dozen hotels is already over $600k, this fine is particularly really meaningless.
Others have stated that it was only one Marriott location. In that case, $600k would hurt quite a bit.