The expense justified as an investment still needs a clear account of what it returns.

Calling a purchase an investment does a great deal of work in a sentence and very little in reality. The word borrows the language of return without committing to any, which is why it appears most often when the case is weakest. Sometimes the return is real and simply unstated, and stating it costs nothing. Where nobody can say what comes back, or when, the word is doing the job evidence should be doing.

Whenever you or somebody else reaches for it, ask for the return in plain terms and a rough timeframe. If the honest answer is that it matters to you, that may be reason enough.