The position you describe isn't in any usual sense of the term, 'nihilism', which is roughly the view that nothing real exists, that nothing is knowable, that nothing is valuable, that there are no objective moral norms, and that nothing is worth doing. (All of these or any in combination.) I don't want to be dogmatic about this characterisation but I don't think any changes someone might want to make to it would connect 'nihilism' with the position you describe.
So how do we label that position ? Hesitantly, I identify it with a version of pragmatism. Pragmatism, which emerged principally in the USA in the late 19th and early 20th centuries, fanned out into a variety of ideas and arguments but it can be roughly characterised as the view that all knowledge and value are subservient to action or 'praxis' (from the Greek). Research pursued solely for its own sake with no practical application is pointless, as is any speculation about what might have been. The sole test of human activity and inquiry is utility, usefulness. 'Does it work ?' is the question : does it (an activity or inquiry) make for happiness or contentment, does it enable successful prediction, does an explanation enable us to manipulate and control the world in ways we want ? Any notion of absolute truth, absolute knowledge, absolute value is just so much metaphysical lumber.
Two points : (1) this is a very rough summary of pragmatism, not nuanced; and (2) I am not putting it forward as my own view. But I think someone holding the position you describe in your question would find pragmatism a congenial philosophy.
Kenneth R. Westphal, Pragmatism, Reason and Norms: A Realistic Assessment - Essays in Critical Appreciation of Frederick L. Will (American Philosophy), ISBN 10: 0823218198 / ISBN 13: 9780823218196. Published by Fordham University Press, 1998.
William James & Castell Alburey, Essays in Pragmatism, ISBN 10: 0028471407 / ISBN 13: 9780028471402. Published by Free Press, London, 1970.
C.S. Peirce, et al., Pragmatism: The Classic Writings, ISBN 10: 0915145375 / ISBN 13: 9780915145379. Published by Hackett Publishing Co, Inc, 1982.