Size can be deceptive, particularly where a boat's purchase and operating costs are concerned.

Let's consider the cost of a sailboat's rig. We'll assume that the annual cost of maintaining and repairing the rig is a fixed fraction of the cost of building the rig in the first place, and this fraction does not change with size- an assumption, yes, but likely a reasonable one for yachts of typical design and modest size.

TL;DR: The rate at which you spend money on a sailboat's rig increases faster than the increase in boat size. This expenditure can be minimized by designing long, slender, efficient hulls that can be driven to good average speeds with relatively small rigs compared to shorter, fatter boats of the same size.