Hashing 24 Terms and Conditions
2.8. Termination. Any particular Mining Contract Capacity allocation shall be terminated by us (i.e., it shall no longer be effective and will not be reinstated), if for 72 consecutive hours the Customer Portions related to such Mining Contract Capacity are less than the maintenance fee for such Mining Contract Capacity. For the avoidance of doubt, you shall be permitted to avoid such termination if you make arrangements acceptable to us in advance to fund the full amount of the maintenance fee during the period when the Customer Portions are less than the maintenance fee.
The Customer Portion = Your Earnings
In other words, they never loose. When mining gets tough (costs more than you earn) you either pay continuously mining fees or you loose your investment altogether.
In this bitcoin harsh period, many customers have lost their "contract" in this way.