I am sorry if anything I have said has offended you.
If you choose to continue to believe that drilling acrylic at 1500 rpm is safe and effective despite your experience then that is up to you. I shall continue to drill at speeds I consider to be sensible. My own 30 years experience has taught me not to believe everything manufacturers tell me.
Whilst I have every respect for David Bates I cannot consider his views to be entirely unbiased since, as proprietor of Stiles and Bates, he sells Colt Pen Drills so has a vested interest in promoting them.
The fact that holding a drill chuck by hand is common practice does not make it good or safe practice.