Would you say that like any fiat currency the bitcoin is generally worth at least what it cost to make it?
Even in times of massive inflation, paper money can still be burned. Obviously it is usually worth much more based on market demand but the lowest value it should command is that which was expended for its creation.
Generating coins costs energy, but you can't turn them back to energy.
The energy you get when you burn paper money is in most situations worth less than its printing costs were.