This, exactly. It's incredibly presumptuous to just throw out a line like they are so cheap so you have no reason to not go out and buy one and if you can't you should just sell your stuff and, with the implication they are somehow a lazy failure, reorganize your priorities. It's ignorant and presumptuous to claim to know someones financial situation and often times it can be deeply hurtful.
Just as an example from personal experience here; I remember when Skyrim first came out and I had saved up enough money to buy it while working 84 hour weeks. I had a ton of debt thanks to some things entirely out of my control at the time, which I will not be going into. I had a PS3, I had a 10 year old 55" CRT TV with a 4:3 aspect ratio and I had, finally, enough money to buy a new game without giving up something else or being irresponsible. I put the game in and was quite annoyed to find it only supported 16:9 resolution and would not letterbox to fit my TV. A good chunk of the screen was just missing and while the game was playable I had wanted to find a solution to the problem... there wasn't one btw.
I got told by so many people online at the time that I had picked an expensive hobby and that if I couldn't afford to go out and just buy a new TV, given how cheaply I could get a 17" HD TV, I should just sell all my stuff for gaming, get a job or stop spending my money on useless shit. You know pissed off I was reading something like that? Not only because it made so many assumptions about me as a person but it completely ignored just the basic realities of any given persons circumstances are something you just do not know - so how dare you try to claim to be better than me or anyone else by telling us to sell our things, work harder, earn more money, or whatever magic solution you come up with like you have us figured out.
Offering a solution to a problem is one thing; the OP needs to buy a new SD card. Telling them they can afford it? Just stop. you are being ignorant. Show some empathy.