The only things unsafe about a hi lift jack is buying some off brand junk version (harbor freight, etc), not knowing how to use it, and/or not using it properly. All tools are potentially dangerous. Buy quality, learn how to use it , then use it properly goes for any tool, even a hammer. To me, crawling under a truck on a trail and jacking up a rig with a bottle jack has plenty of safety issues. At least while you're using a hi lift properly your body parts are not under the vehicle. A hi lift Certainly it wouldn't be the normally appropriate tool for a Subaru, etc... but to make a blanket statement that they are unsafe and not useful is a bit much. They can be quite useful and safe for lifting rigs with larger tires and suspension which would mean a lot of stacking to get the bottle jack high enough and which also means laying under a teetering pile while jacking. Once the vehicle is up, an improvised jack stand can be rolled under without having to ever be under the vehicle. Bonus uses are clamping and spreading when rough repairs are necessary or winching backwards when your permanently mounted winch is on the front of the vehicle. There are countless uses for these tools, but it really all depends on the need. If you have stock bumpers, no sliders and don't venture into rough terrain, then the uses start to dwindle. If you do go on more extreme trails, have added appropriate lifting points like bumpers and real sliders (not show bars or steps), or use the lift mate etc... the potential uses could save the day or at least save time, effort, or potential damage. To me it's cheap insurance to spend the $100 for a quality hi lift and learn how to use it, if you have the potential need.
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