More often than not if you know what a plugin or VST is then you own at least one DAW, and that DAW likely came with an excellent set of stock plugins. The temptation to want more however is a natural thing, but when is it time to upgrade, and is upgrade the correct word?
Studio Reference Monitors are designed to expose everything, whereas speakers are designed to be a pleasant listening experience. If there's anything a little problematic, you need to be able to hear it. Of course the more you spend, the more apparent these problems become.