The bicycle exists because a volcano killed the horses.
After the 1815 Tambora eruption, harvests failed in 1816 and tens of thousands of horses starved or were slaughtered. Karl Drais looked for a substitute and on 12 June 1817 rode about seven kilometres from Mannheim to the Schwetzingen relay house – on a running machine with no pedals, taking just over an hour there and back.
Useful: Many inventions are answers to a shortage, not to a vision.
Source: en.wikipedia.org