And yet, If after ordering that TV for $3,000 you show up at best buy and they say "price went up, now you have to pay $3,500 or lose your $500 deposit for not buying" you'd also be upset. What you're saying is people always want free stuff, sure, I agree with that.
In this case by the way price went up by $2,500 for those who didn't order PUP and went down $2,500 for those who did. If Tesla went with new prices, the first groups would be upset. If they went with old prices, as they are doing now, the second group is upset. Heck, if they announced they will give people who ordered PUP $2,500 worth of credit, you'll still have upset customers - this time those who "just missed it" by a day, a week, a month, a quarter. Even ones who bought a year prior will say "I should get the same credit too since I paid a full,higher price last year". The only way out of this without upsetting anyone is to give $2,500 cash to anyone who ever ordered PUP, and allow those who didn't order PUP to retrofit it for $2,500. That would be some very expensive customer happiness, considering they've sold well over 200,000 cars to date, probably most with PUP.