Why Finland could not simply buy more submarines

Should the Finnish Navy have operated more small submarines in the Second World War?

More boats could help, but Finland first needed the money, construction and support infrastructure, and trained crews to sustain them.

The answer treats fleet size as a system of financial, industrial, personnel, and support constraints. Extra boats help only when a navy can build them, crew them, maintain them, and supply their operating infrastructure. Finland also faced an immediate land threat from Russia, making army spending a dominant claim on limited resources. The exchange is a compact lesson in why an attractive platform cannot be separated from the force that sustains it.