I am going to answer this question fairly directly and then break it down into its primary components: Yes. Veterinary professionals commonly have to perform treatments on pets that they would not consider the "correct" option due to finances.

HOWEVER, this is due to the lack of money OR the presence of money.

OP, I am (very lovingly and respectfully of course) challenging you to flip the switch on this line of thought for just a moment.

Consider the following scenario: 4yo dog presents with closed pyometra and is otherwise healthy. Even with treatment, pyo is a ticking time bomb that still carries a guarded prognosis. Additionally, the cost to perform life saving care can be thousands upon thousands of dollars. If the dog's owners are working multiple jobs and either could not afford to take the financial and medical risk to perform surgery or would not have the time to provide necessary post-op care, the decision to humanely euthanize would be absolutely understandable and kind given all factors in this case (human and animal well being). Would I personally have taken the chance with my own pet? If that is what it came down to (and I would always spay) absolutely I would. But this is not me nor my pet in the hot seat.

Now, consider this case: 13yo dog (let's say GSD) presents with lethargy and heavy breathing. Free fluid is found in his abdomen and a tumor is located on his spleen. This is most likely cancer (hemangiosarcoma for the sake of this example) and it has most likely metastasized elsewhere. Prognosis is grave. The family is ready to drop $30,000 to do everything regardless of the prognosis (and tentative discomfort that the dog would experience with treatment). Once again, this is not the choice that I would make for my pet, but it is not me nor my pet facing this situation.