Cofty, hydrothermal vents would be the last place on earth where life would originate - Vidqun
Actually it is an amazing environment that contains all the conditions and ingredients for life.
As I said before, it probably one of the most inhospitable places on the planet.
No not by a very long way. You are obviously not thinking about alkaline vents.
Secondly, through diffusion in sea water, free molecules would disperse, rather than aggregate.
No they wouldn't. Alkaline vents are made up of millions of tiny pores each a few microns lined with metallic catalysts.
How would life form under such conditions, if it cannot be kickstarted in “perfect” conditions in a lab?
There is no such thing as perfect conditions in the lab. Recreating the pressures, temperatures, PH gradients etc etc is a gigantic challenge. Progress is being made.