Yeah I do a lot of camping and 4x4 and there are some very fancy caravans that are very expensive, there are also smaller more budget friendly ones though. The one thing most people agree is that rooftop tents are not always practical. If you go away every weekend and spend more time away then home then sure, they can be good for that, they are also good for places with animals if you want to be off the ground. What they suck for is fuel economy, road noise and generally needing to find a flat space the size of the car they are attached to.
I think the sweet spot is a high clearance trailer with a fold out rooftop tent and all of the kitchen/fridge etc in the trailer, you get to drive a normal car in the week and then hitch up the camping rig on the weekend. Not the cheapest either unfortunately.