It's the combination of ads, analytics, personalization, and scale.

Ads mean that you want to keep the user on your platform as long as possible. They are incentivized to make it addictive at the most fundamental level. A company selling movies doesn't care how often you watch the movies you buy, they just want to convince you to buy them. A company that makes money for each minute you spend watching a movie would put out very different products.

Analytics mean they can precisely see the effect of any given change to figure out what makes the product more addictive.

Personalization means they can tailor your experience to be addictive to you, personally, rather than just generally addictive to people.

And scale means they can afford to pay enormous amounts of money to a lot of smart people and have them work full time on the problem of making the product more addictive.

I don't know what you do about it.