It's not
quite money into bees, and it's not
quite more human effort.
The problem is that building up a new hive is a lot of work for the bees themselves. A new hive needs to collect its own store of honey, raise the new comb to put this new honey in, and raise a lot of new bees to collect the honey, raise the comb, and tend the bee larva. All of this takes a lot of time and energy, and the bees will not be able to collect pollen and nectar as fast while under-beed, so the bees will produce a lot less extra honey for the beekeepers to harvest.
From a survival-of-bees perspective, the critical point is the point at which you can no longer split the surviving hives enough times each year to replace the ones lost overwintering; we're still probably a long ways off from that point.
From a beekeeping and honey perspective, the problem is that you essentially can't count on hives that are new or were split to generate any extra honey for harvest. This means that you need to increase the total number of hives being kept to harvest the same amount of honey. If you want to be able to harvest honey from 100 hives each year, you may need to keep 400 hives around -- 200 will die in the winter, 100 will be used to generate 200 new hives to replace the ones lost overwintering, and the last 100 you can actually take honey off of, which was your goal all along.