What has been your costliest mistake in this hobby?

Starting and running an audiophile cable company for twenty years. 

to WSRRSW,My most sincere and heartfelt apologies to you.  I wrongly assumed it was a reply by the person I believed I told that lying was unacceptable.  It was not meant for you and I am sorry that I did not ck the post before replying.I never engage in internet war, never, but I guess I got carried away after a long day.  Really, I've told myself lately what does it matter (re many minor irritations) and here certainly about someone I don't know when all this stuff (actually a huge part of my life right now), is going on.  So I don't think I got up on the wrong side of my bed that day, but probably after a 14 hr day and that's the norm lately, went to bed that way.  So once again please accept my apology.
Semper Fi brother  May you have fair winds and following seas.
Mark

My biggest mistake was getting a 'high end' tonearm from Origin Live.  $ Thousands!  It is not better than the standard Technics tonearm on an SL1200.  Origin Live  talk the talk but they do not walk the walk.  The latest version of their conqueror was a pain to set up, impossible to bias correctly and had no sonic benefit.  It was worse than a Jelco.  Short point if you have a Technics TT then keep the tonearm or get a Jelco or SME.

How exactly do you usually bias a tone arm? Eh?

@cd318 thanks for your sympathetic words.  You're correct that these expensive components are extremely vulnerable on my particular speakers.  Tiny protective grills for the tweeters would be helpful.  

After my expensive accident, I've taken to using the mesh grills most of the time.  Unfortunately they diminish the sound quality so I remove them whenever I settle down for serious listening sessions.  As they attach magnetically it only takes seconds to remove them.  My wife prefers the look with the grills on and I do appreciate the peace of mind, knowing there's some kind of protection.