Unfortunately, people are still promoting black hat SEO strategies because they work, at least temporarily. If you're out to make a quick buck and don't care about a future Google penalty, you can get your site ranked well quickly. Individuals who use these tactics sell links on their site to monetize it since Google would catch them if they placed Google Ads on their sites. Shady SEO firms and freelancers also use black hat tactics to show results quickly. They take the money and leave the publisher in the dark about what they really did.
One common scheme black hatters use is buying links. It's very easy to find companies which sell links. Google, which frowns on the practice, lists multiple companies which sell links. The companies claim you'll have links on relevant blogs and websites with high domain authority. It's fairly expensive to go this route. For the same price, you could hire a top content writer to create guest posts for you.
Article spinning is another black hat tactic. You either write an article, have one written for you or steal one from another website and use it to create multiple new, original articles. Google also lists article spinning software in their search results. You could spend a few dollars for an article and put it through the software, which changes words to synonyms, and get unique articles for your website. The only catch is the articles do not read well.
You could start a private blog network. This black hat plan is actually a lot of work. You create multiple blogs in your niche and fill them with spun articles. The sites in your network all link to your money site. Google frowns on websites operated solely to post links.
If you find any questionable advice online, review Google's Webmaster Guidelines. They tell you what to do and what not to do. It's the only place you're guaranteed to get advice which won't get your website penalized. For more information click here https://www.reddit.com/r/SEO/comments/cbd8bi/hackstobeavoidedfor_seo/.