when you bought the Tesla for 6.59229 BTC did you give them BTC or did you cash out 6.59229 BTC for USD and give Tesla the USD? If so, your truck has lost no value as it is the worth the same amount of USD - give or take.

In this scenario, they gave you BTC and expect ROI in BTC, your goal was to return them BTC - the fact that BTC is worth more or even it was worth less USD is irrelevant - their BTC investment should be worth more BTC than when they gave it to you.

It sounds like since BTC has gone up in value the decision was to give the seats less BTC because it is "worth more USD" that way you could keep the majority of BTC for yourself? I could be wrong - I have not seen the books to know if 100% of the mining rewards (minus the agreed upon percentage that goes to you) has gone to the seats or not.

If the full amount that should have gone to the seats has gone to the seats, then it was a bad investment based on the actual BTC return to date. They would have been better to invest it elsewhere or to just HODL it.

A good example would be the individual who paid 1.65 BTC and has received/earned only 0.00950615 BTC in return. that is a loss of 1.64049385 BTC