So if I understand it in it's strictest terms, this wording means that if the character looses concentration, the slot is spent.  I say that because in some places in the rules, it specifically tell you when it does not cost a slot.  That means that if it doesn't say that, then it does, correct?

"When you Ready a spell, you cast it as normal (expending any resources used to cast it) but hold its energy, which you release with your Reaction when the trigger occurs. To be readied, a spell must have a casting time of an action, and holding on to the spell's magic requires Concentration, which you can maintain up to the start of your next turn. If your Concentration is broken, the spell dissipates without taking effect."

The spell slot is still expended if you lose Concentration, yes.

The part about "expending any resources used to cast it" means the spell slot is expended immediately when you take the Ready action. Losing Concentration before the spell actually activates has no effect on that.

There's also a SAC answer about it:

How does readying a spell work? Do you lose your spell slot if the trigger never occurs?

When you take the Ready action to ready a spell, you immediately expend any resources used to cast said spell, including any spell slot. You don’t get any of these resources back if the trigger never occurs. See appendix C of the Player’s Handbook.