From PIE *welh₁- (to wish) — originally a verb of desire, not futurity; same root as 'wealth' and 'voluntary.'
Expressing the future tense; expressing willingness, desire, intention, or inevitability.
From Old English 'willan' (to wish, to desire, to want, to be willing), from Proto-Germanic *wiljaną (to want, to wish, to desire), from PIE *welh₁- (to wish, to will, to choose). The same root produced Latin 'velle' (to wish, to want), 'voluntās' (will, willingness), Greek 'elpís' (hope, expectation), and Sanskrit 'vṛṇīté' (chooses). The shift from 'wish, desire' to future tense marker occurred because statements
'Will,' 'wealth,' 'well,' 'voluntary,' 'volition,' 'benevolent,' and 'malevolent' all come from PIE *welh₁- (to wish, to choose). 'Wealth' was originally 'well-th' — the state of faring well, of having one's wishes fulfilled. 'Voluntary' is from Latin 'voluntas' (will, wish). 'Benevolent' is 'wishing well' (bene + volens). Even the name