'A lot of people' usually means the predominately older strata of society. Japan has been having issues with the younger generation being locked out of employment and advancement because of older generations needing to hold onto their career with a death grip and retirement ages going up.
The aged society scam can only persist as long as they can exploit the younger generation. When that collapses, the end result is either going to be leaving the elderly to die or things start collapsing in new and interesting ways
The only reason why people 'prefer' this is for the same reason 'prefer' to believe climate change doesn't exist. Eventually reality catches up.
You've completely missed my point.
Immigration is not a long term solution to an aged society. The societies of target countries are aging as well and not far behind.
What you advocate is to bolster the work force of a country with a fertility rate of ~1 and falling, with people from a place with a fertility rate of ~2 and falling.