Every couple of months this comes up.
The navy took the conscripts the army didn’t want, besides, the army was regional, the navy was federal. The navy was a nation building exercise and a way of uniting the German diaspora across the world that numbered in the millions. You need a German brand promise for the new nation to buy into not a Prussian one. Eschewing a navy means Germany places all it's foreign investment, imports and exports at the trust of GB. Treitschke would roll in his grave.
Building the HSF also demonstrated German efficiency and
political will as Germany spent less on the navy than the French and yet managed to overtake the French navy.
Army vs Navy industrial benefits
Artillery manufacturing: pipe making and some peasants learn maths.
Naval ship building: bigger pipe making and a business case for computers.
Also: extensive electrical systems, motors, hydraulics, engineering pressure vessels, boiler making, fuel systems, pumps, turbines, internal combustion engines, batteries, electric motors, riveting, welding, forgings, castings, advanced metallurgy, high tensile steel, plate bending, precision optics, mechanical analogue computers, communication systems, wireless, furniture making, refrigeration, woodwork and decking, galvanised fittings, painting, cutting edge engineering, advanced chemicals in anti fouling paint, drafting, project management, industrial scale organisation etc. All usable in the wider marine and broader economy. 40% of warship costs go into the pockets of yard workers who pay taxes and so the whole thing goes around again.
More tanks, what tanks? No army invented the tank -
it took a navy to do that. It required brains, insight, planning, high engineering skills and a mature military industrial complex to achieve. To an army, tanks just frighten the horses and detract from the 'spirit of the bayonet'. The genesis of the heavy bomber also came from the navy with the spec for 'a bloody paralyser of an aircraft' - the Handley Page Type 0 coming from the RNAS.
Taking the money from the Navy and diverting to the Army would probably result in just conscripts with more money - and consequently higher incidents of VD. You'd shrink Krupp so it would just be a Skoda rival. A bigger German army sooner and the bombastic rhetoric that would follow would probably result in a cold war of Europe united against Germany with GB aloof of it all. Perhaps even the Austrians as they had also been a target in the German wars of unification just like all it's other neighbors except Russia.
In terms of shifting capabilities within the navy, long term lifecycle costs make battleships and battlecruisers more cost effective. Based on RN figures, German probably similar. For each BB or BC you may get 10 subs.
Same figures post ww1: