This is absolutely a valid warning, but I think it is worth mentioning (& maybe it has already been discussed here, I've just registered and not scoured this thread exhaustively yet) that
dxm has recently undergone clinical trials (one example
here but there are others as well) as a treatment for major depressive disorder & is currently being prescribed in a formulation with wellbutrin (aka bupropion — a dopamine and norepinephrine reuptake inhibitor iirc) for daily use under the brandname
auvelity. I have had great success using it in therapeutic doses of 30mg
dxm freebase every 12 hours (you can read more in my comment
here). I'm currently on about week six of the regimen with no ill effects — the mania was bordering on excessive during weeks 2 & 3 when I was taking about 120mg daily of hbr (sick with cold which is how I stumbled upon this for the second time) has settled down since I switched to 60mg freebase daily.