We gain a lot of benefit from them doing so. Do you like your cell phone? You know where it came from? Sure, once transistors were figured out, transmission of radiation understood, computing technology necessary for cell technology a private company took over and invested time and research into developing cell phones as a consumer product. But it didn't poof into existence. The base research needed to get to that point was tremendous. Some of that research panned out, some didn't. But we do not have the benefit of hindsight when making these decisions for funding.
The end is the same. Scientific research is a net HUGE plus for all of us. We all derive benefit from engaging in it. But it is not necessarily profitable, and it's on time scales far too long for any private company to consider. Yet even without it being profitable, it provides massive benefits to us all. That is why government is government and business is business.
I understand the underlying philosophy of thinking government should be more responsible and more "business like". But all those underlying premises fall victim to fallacy of aggregation. You can think of specialized cases when this can work out better for private industry. But if you aggregate it over the whole, and see the system for what it is; it becomes obvious that private business cannot support this. It can only be supported by something with functionally infinite pockets and infinite time; that is government.