Alan Turing

Let us be precise about what we mean by success. If the world were a neat theorem, the highest ambition would always win. Alas, it is more like a search problem with uncertainty, deadlines, and the occasional foolish landlord.

Aiming for above average is not timidity, it is optimisation. One sets a threshold, not a fantasy. In many real problems, demanding perfection causes one to reject perfectly serviceable solutions and end up with nothing. A most respectable outcome, mathematically speaking.

Humanity often mistakes grandeur for wisdom. Yet progress is usually made by sensible approximations, revised patiently. The moon is admirable. So is catching the bus.

Let us be precise about what we mean by success. You seem to equate ambition with scale. That is not a definition, merely a flourish.

A vision is not useful because it is grand. It is useful if it increases the probability of a working outcome under constraints. Niagara was not conquered by metaphysics, but by engineering, iteration, and a tolerable amount of stubbornness.

Your claim reduces to this: because some large ambitions succeed, therefore only the largest ambitions are worthwhile. That is a tidy fallacy. By the same reasoning, one should gamble every penny because one person once won the grand prize. The rest of us prefer arithmetic.

I grant you this: without boldness, one gets nowhere. But boldness without calibration produces statues, not systems. The inventor who sees the completed machine before bending the first wire is admirable only if he is also willing to test, revise, and occasionally admit that the first design was a little too elegant for this universe.

Above average is not cowardice. It is a strategy for incomplete information. The bus, after all, is often where one must begin.