It's a modest and pretty easily manageable problem now, but it will become pretty non-trivial in the future if not properly handled. However, all signs point to it being properly handled (it's in everyone's interest), so my advice to laymen is to not worry about it.
It's true that even near-Earth space is crazy, crazy big so that the amount of volume occupied by debris is extremely tiny, but what's also true is that debris is moving fantastically fast so that the volume "effectively occupied" by debris is only small rather than extremely tiny. This cashes out in the empirical facts (which fit perfectly with our models) that there have been four unintended collisions between satellites and debris:
These have all taken place in the past 25 year (despite > 50 years of spaceflight) because the density is increasing. If the density keeps increasing without the forthcoming mitigation efforts, the rate of unintentional collisions would keep rising to bad levels.
Going by the maxim of “Space is always more empty than one could possibly imagine.”.
>inb4 “if the moon were a pixel”.