Before DSLRs, I was a child of the 80s and my main camera beforehand was a Canon AE-1 SLR (great all round 35mm...back in a time in which any SLR could have the same IQ dependent on what film stock). My first introduction to digital photography was when I had an internship at the New England Journal of Medicine, and they had one of the Nikon body/Kodak digital backs. At the time I was really amazed how volatile exposure was: as memory serves, it was a 2MP TIFF RAW....the camera had an external flash: any kind of misalignment with the flash (or underexposure), the image was really pixelated. My next camera was a 5MP Sony Cypershot with Carl Zeiss lens: it actually was really good for the time: it even had an infrared nighttime mode for easy focus in dim light (and if I could try to take any of those images and look on my HD or now 4K screens, I'm sure I'd be shocked). However, at the time, the noise wasn't bad for 400 ISO. I then got a Nikon point and shoot: it was really terrible: even ISO 200, I could see bad pixelation. When I saw that there was a FF DSLR within an approachable range for me at the time, I went ahead and invested in the 5D. It was partly that it allowed me to not need to ever get used to a crop with how I understood lenses, and that the 5D was really revolutionary for performance and "value" for FF. At the time, I was in my mid 20s, a young professional, who was having enough salary to just save and allocate enough into photography as a serious hobby. Since then, I've acted as backup photographer for weddings and such, and have done head shots at work, but I'm still serious amateur. I'm skilled enough that I have good calibration from screen to my prints. I line my cubicle at work with quite a few prints, so it's a topic for many folks passing in. I've noticed the ones who do ask what my equipment is also tends to be the ones who have invested in a DSLR (usually a Canon Rebel). Anyway, for me, the 5D3 and 5D4 models are the best for my uses. Back when I got the 5D when new....I was blown away with its high ISO, but had to get used to its low DR and really found its AF limiting.
When it comes to professionals with more money than sense....it reminds me of a review I once happened upon with the 5D3. The review was from a lawyer. He bought it when it first came out, and had a whole blog post about how awful it was. Basically, he blasted it because it didn't look great in green mode (full auto) compared to his phone camera. Bear in mind that this was before the latest advancements with phone cameras. I'm seeing on TV there's the iPhone ads about night photos: even on my 4K TV.....it seems they are a bit pixelated. Don't get me wrong: great improvements with DR for a small sensor....but still much lower MP compared to dedicated camera.