In the grey hat SEO world, the thought is that you can take a domain that is keyword driven, do a quick optimization to get the site ranking, and sell it off at a profit. It could, and does happen daily. How much time is invested in optimizing a site to get to page one, vs how much the site will sell for? (remember that quote at the beginning of this article?). Let's put it into simple math:
Something wise my father once told me "Something is only worth how much someone is willing to pay for it." This small seemingly unimportant statement has guided me in many selling and purchasing decisions in my life. Sometimes, it makes the reality all too apparent. So, is buying a domain with the intention of selling it a good idea? Let's break down the details, and talk to some people that actively pursue this method. Yeah, we know a guy.
Whether you can use an existing backlink profile for a new web project under the available domain depends on whether the link target of incoming links can be reconstructed. In order to analyze which content was provided under a domain in the past, you can find out on the Internet Archive Backlinks have no value if they lead to nowhere and this can even have a negative impact. They are possibly redirected to similar subpages or homepages using 301 redirect. In this case the most part of the link’s power is lost.

Great post! I tried to repurpose an expired domain to build an authority site (your method 1) – but it doesn’t rank as it should. i checked the backlink profile via majestic and and it’s clean. also checked the metrics of the competition. with the amount of trust and link juice my expired domain has vs. the competition, it should be on page 1 for those keywords. is there something i’m missing here?

Another point of concern is that many people feel that squatting or registering domains is unethical. This is because many web developers have a hard time finding relevant domain names for their projects since most of them have already been registered. Many corporate giants also frown upon the domain flipping industry because many domain names relevant to them are already registered.
If domains are real estate, then the same rules of real estate should apply. In real estate, taxes are based on the value of the property. So, a person asking $10,000 for a domain shouldn't be paying the standard $15-30 renewal fee as a person asking $200. The renewal fee should be based on the domain's value. Domainers want to claim it's like real estate without applying the most fundamental rules of real estate.

In theory, you could technically acquire a domain for $10,000 and be able to sell it for $100,000. You could also acquire a domain for $10 and be able to sell it for $100,000, $10,000… or $100, you get the picture. Because of this, it’s hard to recommend a perfect starting budget because your strategy, experience, and the pace at which you learn will hugely affect your buying and selling decisions.