The Emphasis is on 'Free!'
Operators of illegal sites often couldn't care less if you pay for their so-called services. Their primary goal is to get you to click the ads or to download iffy software from their servers. That's why they use huge fonts and flashing graphics to emphasize the word "free."
Free, of course, is a trigger word that sends many consumers into a mouth-frothing frenzy. Click a few links for a free movie? Why not? Oh, I have to click on a bizarre graphic for Indonesian cheesecake first? No problem!
That's exactly the mentality that illicit site owners hope you'll follow. Legit sites, on the other hand, lure users with a few streams but hold the good stuff closer to their vests, hoping you'll ante up for a subscription or at least a one-time fee for the right to play their content.
Keep in mind, there are some legitimate sites that offer free content, such as Pluto TV, Tubi, and Crackle, but you may have to watch commercials. Others (like Kanopy) require a library card or a college .edu email address to watch. And you can usually watch the biggies like Netflix, Hulu and Amazon Prime for the first 30 days for free. Just remember to cancel your subscription before your time is up to avoid charges.