The individual immune response varies but generally speaking, all of the vaccines used in the west* produce a stronger immune response than from getting covid itself. So the vaccines provide "more" protection than what you have currently. What you've essentially gotten is equivalent to the first dose of a vaccine - maybe slightly stronger - but not the second. As a result, people who've had covid get essentially the same level of protection from vaccine dose 1 that non-covid people get from 2, and there is some evidence to suggest that vaccine dose 2 is kind of redundant for you - that's the closest reality to what your mate's describing. But dose 1 at the very least makes a big difference, both in the volume of antibodies (can be as much as doubled from the vaccine) and it is highly likely it will produce a longer-lasting immune response.
*one of the Chinese ones didn't in phase 3 trials, think that's the only exception but not sure about some of the other ones produced for domestic consumption in e.g. India