Good point. Of course it's possible that 7X is a cost that cancels out the revenue from those customers, in which case it would be better not to offer the option, but as long as it's not, it's still profitable to offer the plan. Depending on the ratios, the cheap customer bracket could even be more profitable (in absolute terms, as you say). You just have to build the extra support cost into your pricing.

$9 customer - $5 support = $4 per many customers

$199 customer - $1 support = $198 per few customers