First of all, the SpaceX plans on colonizing Mars are not built onto the asumption, that the project is funded by the taxpayer, that is, draining the resources

First of all, the SpaceX plans on colonizing Mars are not built onto the asumption, that the project is funded by the taxpayer, that is, draining the resources of a nation. They plan to fund the project by the money they are making, like for example enabling global internet access via Starlink. So even if SpaceX never makes it to Mark, it would be a benefit. And of course, reaching Mars would indeed have many benefits for humankind. First, there is science of course. Why are people living at the south pole, there are nicer places on Earth? Science. Then there is the huge gain in perspective. Even if the direct utility of all the space missions might not be large, looking onto our planet has given us a clear perspective. That we shouldn't waste this precious place. Finally, not at least trying to go to Mars and beyond would have a negative impact on the long-time development of the species. We either eventually leave this planet or eventually will be consumed by the expanding sun. Sure, there is plenty of time till then and I hope there are others why try to make humankind eventually an interstellar species. But if we don't even try, because it is "stupid and wasteful", we already have lost. And I am sure, even if the colony on Mars might not do anything useful in the short term, just having space launch capability available as the article describes, will find many other beneficial uses.