....One dude just went "why can't you let people enjoy their purchases".....
On one hand that is a valid argument. If I've already spent the money and am happy with the purchase then why try to make me feel bad about it.
On the other hand, since they are posting online about the purchase and their amazing results, they are telling others that their purchase was a good investment and thus pushing for others to do similarly.
This makes it so any effort to share a counterpoint is both helping to inform others and taking a dig at their purchase. There is no way to warn others without saying their purchase wasn't smart. But, it isn't as
if you went to their house and off the cuff told them they wasted their money.
They were publicly bragging about their purchase and should be able to handle other opinions; especially mild ones like the way you said you worded yours.
Keeping in mind that the 'saving others' thing often becomes the attitude of "why would they ever make a component like that?" simply because an amp doesn't put out the power that you want or because a speaker can't play at the levels that you want even thought they perfectly fit the buyers needs. So the over the top saving thing tends to cause a lot of the issues with the smaller 'you only need this' comments.
I wish I had read more posts with the other side about 'upgrades' before I spent a lot of money on fancy capacitors, wire etc. Like all things anymore, the herd mentality and the need to belong is strong so we separate out into groups and don't like having our group view questioned.