So based on your theory, you might as well just buy some £5 earbuds then?
If you don't value the music you make or listen to, then yes, don't spend money on equipment and instead piss it up the wall whilst you give away your music for free.
I have had £300 monitors for around 10 years. I then upgraded to something much better and I wish I had done it sooner. The AE22s are probably the best sub £1000 speaker and punch above their weight.
Your argument becomes pointless when you state:
Obviously you need to do some checking on high end monitors
My point is that near-as-damnit-perfect results can be achieved on a £200-£300 pair of monitors, which will also suffice for "high end checking" if you get reputable ones (i.e. not M-Audio or Behringer ones imo). Yes, you
will probably find it easier to mix on something better (not necessarily more expensive though
) but imo one needs a lot of experience to really take advantage of the extra clarity you get from breaking the £1000 barrier. I honestly think you don't need to throw more than Rokit 6s or MSP5s at a home production setup. imo.