It's the same with rats. Google will tell you that rats live 2-3 years and can live up to 4 years with good care. The reality is that 2 - 2.5 years is much more realistic, even for well looked after rats that receive good veterinary care. I keep rats and I'm active on lots of rat forums, several surveys of very keen rat owners have shown that rats very rarely live to 3 years (https://www.neratsociety.co.uk/html/longevity.shtml. I take all of my rats to the vet when they need it, I research the food I feed them, give them a lot of enrichment etc. My oldest rat so far has been 33 months and most haven't reached 30 months.
I think a lot of people exaggerate the age of their rats, hamsters, mice etc (I don't know why!) and I wouldn't be surprised if it's the same with guinea pigs. The misinformation makes people feel bad when they're giving excellent care but their pet only reaches 2 years. Joining a forum with other really engaged, enthusiastic owners really helps as then you get more genuine information.
Also it's been in the news that the big companies that have taken over most vets are not offering value for money, I'm not sure why anyone thinks it's reasonable for them to be making such enormous profits. Money is not always an indicator that people will treat their pets well. To all the people saying that it's a good thing that pets are so expensive as it weeds out bad owners - plenty of rich people neglect their pets. And if vet bills are going up so much year on year then how can people plan? Pets are very sadly being taken to rescues by caring owners who could afford vet bills when they bought the pet, but can't afford them since they skyrocketed. And they will stay in the rescue for longer if the average person is put off due to unaffordability. It is wrong IMO for these big conglomerates to be making such big profits.
And up selling does absolutely happen but it's not all vets. I took a rat to a vet with a suspected UTI and was told they would have to sedate her to get a urine sample from her bladder invasively, it would cost £400. I asked why can't I just bring you a urine sample, they said it could be contaminated. The vet I go to now just asks me to bring in a urine sample for a suspected UTI, no expensive and invasive tests or procedures. Sedating a rat is quite high risk so the upselling is not in their best interests either, it is just immoral.
I go to an independent vets now and I trust them a lot more.