The big cloud platforms offer a rich selection of different offerings, which (just like in every other industry) cross subsidize each other.
When I go to a restaurant, I don't expect that they will be making the same profit margin on every item on the final bill, and in fact, they almost never do. Drinks tend to have a very high profit margin, some labour intensive items may be a break even at best, and the complimentary bread sticks or chips and salsa (if offered) will certainly be a loss.
I guess I could write a very upset article about how my local mexican restaurant is SERIOUSLY SCREWING ME OVER with their drink prices, but if I don't write the companion piece about their cheap burritos (subsidized, of course, by the drink prices), it would only show half the picture.
The reality is that I'm buying a whole package (at AWS or a restaurant) and I should evaluate the whole picture. Yes, I can get bandwidth cheaper outside AWS (or a can of coke a lot cheaper from a big box retailer). But I can't really get the total package of integrated, managed services outside AWS (certainly not for the cost they charge), any more than I can get someone else to show up in my kitchen and cook a three piece meal and then do all the dishes. (Which is to say, I totally could hire a chef to do that, but it would cost me a lot more. I could BUILD an internal SQS clone if I had to, but my employer would never break even on the cost of getting me to do so.)
AWS is very cheap for some things and very expensive for others. Depending on your usage and workload it may or may not be economical to buy the package they offer. If it is, go for it. If not, don't. Just like, you know, every other good or service you purchase in both your personal and professional life.