I'm going to let you in on a fact that is not necessarily immediately obvious about our site: Most of the questions here in Personal Finance & Money are opinion-based. The reason for this is that personal finance is only partially about math. Personal behavior weighs greatly in personal finance, and the "correct" approach in any situation will involve opinion. Almost any question about budgeting, investing, or spending will involve at least an element of opinion. Even something like tax law, which you might think should be black-and-white, cut-and-dried, often involve opinion to a great extent. (Exhibit A)
"Primarily opinion-based" exists as a close reason network-wide here on StackExchange, but different sites have different criteria for actually using it. On a site like Worldbuilding, every question is entirely opinion-based. For them, they have identified specific criteria that a question has to meet to be allowed. With other sites, such as programming, science, and technology sites, most of their questions are entirely objective, with a minimum of opinion. Even on those sites, however, there are plenty of questions that involve opinion to make an answer. (Exhibit B)
For our site, we have decided that we don't allow questions which are asking for predictions into the future. Asking "Should I buy XYZ stock?", or "Which is a better investment: Apple or Google?" or "Is now the right time to buy gold?" are all closeable as primarily opinion-based because there is no objective answer possible without a time machine (or at least a crystal ball). Sure, someone could come up with something that sounds like an objective answer using past performance, financial statements, etc., but we have decided as a site that we don't want future prediction speculation on our site.
However, we do have open-ended advice questions on our site all the time, and these are not off-topic. Indeed, they are among our most highly rated, interesting questions. (Exhibit C, Exhibit D).
In my opinion, the question you are pointing to falls under this category. The value of time is on-topic for personal finance, and although the topic is a matter of opinion, the answerers have proven that it can be discussed rationally and objectively. It is a very interesting question that I hope does not get closed. If it does get closed, I will vote to reopen.