Why Is AT&T's Internet So Intentionally Slow

I've been a customer at multiple addresses with AT&T for over 6 years now. I am an IT professional with a bachelors in CS, and I've been building and working with computers since I was a child. Yet with all my troubleshooting experience and all my knowledge and experience, I constantly have issues with your internet service - and it's the same issue despite the equipment I'm using, the location, etc. No matter what, there are periods where my internet is just horrible. Currently I pay for 25mbps as that is the highest they can offer in my area. At least a few days a week my internet drops to under 5mbps, often under 1mbps, and this can last anywhere from 6 hours to days. My parents also have AT&T and their internet was under 5mbps for over 6 months, despite them paying for more. 

The solution? I have to call AT&T and have them do something on their end. It works every single time. They run the standard tests, nothing works, then they say "Hold on while I try something else" or something similar, then voila ~ it's fixed! Why is that? Why is it that the same issue occurs constantly and the only way to fix it is for them to manually change something on their end? It seems like intentional internet throttling. They've charged my poor parents for new equipment and service charges, completely taking advantage of an older couple unfamiliar with the technology, when all it ACTUALLY comes down to is a flip of a switch on their end. I now have control of my parents' account because of this. What's the solution when they have an issue? You guessed it! I call, they run the same tired tests, then after finding nothing they miraculously fix it with the press of a button. 

So, AT&T, why are you so horrible to your paying customers? Do you not care that after moving I will never come back to your service? That my folks will do the same? That, as the IT professional my friends and company comes to for advice, I will always recommend going with someone other than AT&T?  Do you not care that word continues to spread about your abuse of customers? 

Why are you so content with taking advantage of your customers? I'm amazed that these practices are legal. I'd love to hear some sort of explanation.