Did someone need to downvote me to disagree with my opinion? What kind of person are they?

Now, some points.

  what economics is a science now

Are you kidding? 3D-animation is not a science but you still can understand how it is done and what works better and what doesn’t. Economic life is a physical process that has been observed for quite a while and some patterns appear to have been understood. We may not be right in 100% of cases but the fact is, that consumption has been a crucial factor in (at least) some instances of economic growth in the past.

  how much can you control the effects of whar you consume other than by controlling how much

That’s easy. By choosing alternative products/services. You boycott companies that are not doing too good of a job and support those (“vote with your wallet”) that you believe to be doing better.

  You might buy vegan patties…

That part looks a bit confusing to me. But in my example I was talking about things that I deem “actually relevant to moral questions”. (It depends how you define the term “moral”, I suppose). But to me a life of a sentient being that has individuality trumps many other concerns related to political ideologies, people’s convenience, etc.

  you only have partial power over it's good-faith nature

“Its nature”. I do not think that this part of the argument looks so clearly-defined. What is “partial” versus “non-partial”? To me it’s all “partial” and it’s “good enough”. I’ll take “partial” any day! Besides, in any case you still need to eat and you still need to make those choices.

  If you really want to keep your hands clean

That’s definitely not the ultimate goal or a cornerstone of my ethics or “philosophy”. In general I am fairly concerned with people who pay too much attention to “cleanliness” or “purity”. Not really an argument, just a note. :)

  more than you absolutely need to for your survival

I think, it’s really cruel to expect someone to spend their lives only at physical survival level. People do have needs beyond physical. So it makes it necessary to spend “beyond that level” and therefore it makes this “morally ambiguous act” necessary. But that’s what I said! We are back to a “very general philosophical level” and we are discussing that “(almost) everything is morally ambiguous”. Yes, I agree with that. (But I also think that it’s a fairly useless question compared to a very practical question, “Do we need to consume to make our friends’ parents live longer and happier?”)

  we absolutely need the economy to grow for continued prosperity

Could you define “continued prosperity”? Do you propose to just stay at the same level we are on already? Or do you propose to go back to a level where many people with serious diseases (who depend on high-tech medicine and equipment) to survive every day will not survive? By the way, I was not speaking about “continued prosperity”. I was talking about “better prosperity”. There’s too much suffering in the world currently in my opinion! We need better medical technologies, we need “cultured meat”, we need robotic helpers for old lonely people, we need to make Earth-born life multi-planetary (or multi-space-habitat) otherwise it will be gone in several hundred million years! Again, opinion. Please don’t “argue” with that!

  preposterous

Preposterous means “utterly absurd”. You could argue that the statement is dubious probably. But to call it “absurd” right away… The statement might actually be true. It might actually be “the only way for societies on certain stages”.

  It's clearly A method

I agree with this! Meaning, it might not be the _only_ method. There might be some nano-robots that make stuff for people out of the air and then no one needs to compete and do unpleasant work and everything is so good, yadda yadda.

  a glorified Ponzi scheme 

Now that’s actually interesting. Do you have links to any serious works which show that economic growth (in all circumstances) is 100% a Ponzi scheme? Because when there’s such a scheme in an economy it’s called “a bubble” and it’s recognized as its own thing and then there’s an argument that sometimes bubbles are not so “bad” and that they might contribute to economic growth (whether we say that economic growth is a good or a bad thing). But again, it’s dubious to me that every instance of a growing economy is 100% a “bubble”.