If you see someone selling ebooks on Shopee, especially if they’re popular titles by relatively large publishers and not something self-published, those are likely pirated copies. Ok, not just ‘likely’, they’re almost definitely pirated. Publishers tend to sell on their own platforms, or on Amazon or Google Play or Kobo and the like.
Books are expensive, I get that. But if you’re buying those pirated books, you’re not only funding someone who had nothing at all to do with getting those books out (except possibly crack the DRM so the books could be distributed illegally), you’re also not paying the people who actually did work on the book. You think, eh, it’s a big publisher, it can take a hit. But it’s not just the publisher. Publishers engage writers, editors, proofreaders, illustrators, designers, typesetters, printers, the people who do sales and marketing, system administrators, accountants, analysts, receptionists, security guards … you get the picture.
You want free ebooks? Try the library. Try Project Gutenberg for older works that are no longer under copyright. Follow Twitter accounts of authors or publishers—sometimes they announce free or highly discounted ebooks. There are options out there.