Jetpacks are only useful if there is no infrastructure. You can get a motorcycle for <$500 that is infinity more useful than a $500,000 jetpack. Hop on the road and get where you want in a moment.
Plus a jetpack requires special licensing and pre approved flight plans, ect.
Jetpacks are only a toy, a very, very expensive toy as they are now.
A Honda Grom is still $3500, but I don’t think that weakens your point about cost. However, similarly to jet packs, autogyros, ultralights, and paramotors, motorcycles are not as popular in the USA, due to safety concerns. So even though motorcycles are very useful and cheap, people don’t ride them much. I think the same would be true of a $3500 jet pack.
it's rather $300,000, but at the burning rate of several litres of kerosene per minute, your budget isn't far off reality of actually owning one and using it.
Plus a jetpack requires special licensing and pre approved flight plans, ect.
Jetpacks are only a toy, a very, very expensive toy as they are now.