If you smash them together faster, you just increase their energy, i.e. the opposite of what you want. If electrons fly off, you are likely to be left with an unstable molecule.

But in a covalent bonding you're sharing electrons, which means you need less electrons than in the atom state.

I sort of see what you are trying to say, but I think you're slightly misunderstanding what is going on. It is true that you are sharing electrons in a covalent bond, but it is not correct to therefore say that you need less electrons than in the atom state. A simple example: say you have to H atoms. Each has one electron. You put them together and form H2, which has two electrons combined. In both cases you need a total of two electrons, in order to have a neutral system. If you change that in any way, you will end up with highly reactive species (e.g. H+, H-, H2+, H2-). H+ is of course just an acid.

What you are probably thinking of, is the fact that if you put NaOH, or HCl in water, you get Na+, OH-, etc., and these are more stable than their neutral counterparts. But this is because they are stabilised by (polar) water molecules. Outside of water (or some other stabilising solvent), Na+, OH-, H+ and Cl- are all very reactive species.