Well as the saying goes "Demand, is the mother of invention".
So - why? That is where is your demand/need?
Tanks were invented/developed to break the impasse of trench warfare of WW1 - to cross and break the entanglements of barbed wire, to destroy the machine gun posts that guarded 'no-man's land' and enable a breakthrough of the enemies defensive position.
Before WW1 no one anticipated what industrial warfare would look like. The only model had been the American Civil War, but the Europeans didn't think that applied to them!!
The other 'model' was the Russian v Japan war of 1905, again too far away to be of relevance to Europe!
Plus, you need advances in the internal combustion engine, to make it possible