What are the consequences if you sell links from the site?

Question

Search Engine Optimization

Google and read different articles, like "How to make money selling links?" etc. On each page he writes differently, you can earn a lot without harming the site, and the article convinces that this is so. On the other site, it's the other way around. Because I am new to this business, and I had to read a lot of articles about making money by selling links, and they misled me. And I would like you to answer a couple of my exciting questions:
1. What are the consequences for the site if you sell links? Can a site be permanently blocked?
2. Is it possible to earn money on this, namely to earn, and not to earn extra money? Can income be turned into passive income?
3. What should be the TIC, PR, cash contributions, and how many pages should be on the site to earn 100 bucks a month? Does a site have to have unique content to make 100 bucks a month? How much time does it take on average, if not straining, to reach the point where you earn 100 bucks a month selling links?
Please answer all questions if you can!
By the way, if it's not a secret, how much did you earn by selling links? How long did it take to reach such heights? Would you recommend this type of income to someone? Why?

Answer 1

Links are already of little use for SEO, so this activity turns into shit, because. demand drops sharply. But a site with a lot of external links runs the risk of falling under the filter and flying out of the search results and never returning there, which is correct, because these sites are usually not useful. You can earn from the site in other ways if you visit it - these are affiliate programs or direct, banner or contextual advertising, teaser (although the latter is also slag in 90% of cases).
The advice is this:
1. Make a good and useful site
2. If there is traffic, there will be money, so pay attention to this first, and only then think about how to make money.
3. start slowly monetizing the site
4. Find a way to get a visitor for less than the expected income received from the visitor.
If the project is really good and unique, then it makes sense to try to sell it or attract investments, but this is not easy either.
Good luck.

Answer 2

If you do not greatly reduce the cost of links, ie. sell less, but more expensive, as well as place them organically on the site (not in the footer), then the chance of negative consequences will be minimized.
It is even better to place contextual links (inscribed in the existing materials on the site), or post thematic articles with thematic links of advertisers.
The last option, if you do not overdo it and dilute it with non-advertising articles, may even have a positive effect on the attitude of search engines to your site.