Some people who get the flu (especially the very young and very old) need IV fluids, but they’re generally quite sick and belong in a medical facility. Most people who have exercised a lot, have a hangover, jet lag, or the flu can drink the fluids they need. While I’m no beauty expert, I doubt that IV fluids will improve the appearance of a person who is well-nourished and well-hydrated to start with.
And it’s worth emphasizing that the conditions for which the IVs-on-demand are offered are not conditions caused by dehydration or reversed by hydration. For example, jet lag is not due to dehydration. And while oral fluids are generally recommended for hangover symptoms (among other remedies), dehydration is not the only cause of hangover symptoms.
Finally, there’s a reasonable alternative to IV fluids: drinking fluids. If you’re able to drink fluids, that’s the best way to get them. If you’re too sick to drink and need rehydration, you should get care at a medical facility.