Yeah, in USB rechargeables the minimum I've used on the bike itself is the Cygolite Hotshot 50, and it still costs just a few pennies shy of $30. When I bought it the Hotshots 80 and brighter were still much more expensive. But now you can buy the 100 and 150 for less than $40, so there isn't much point to the 50.
The Hotshots are so lightweight I'll probably buy a 150 to mount on my road bike as a second light, under the Hotshot 50. I'll keep the 50 for nighttime group rides. It's more group ride friendly, especially aimed downward a bit.
A little trick I learned from watching other folks is the piercing flash of the brightest Hotshots can be minimized a bit without sacrificing visibility. Just aim them downward a bit -- the mounts are adjustable. The bright light flashes off the rear tire and pavement, which actually increases visibility without blinding folks directly behind us.
Last week I participated in a fairly fast nighttime ride, including twisty sections of the MUP where 12 mph would feel fast. I had to pass or drop way behind a couple of folks whose Hotshot or similarly piercing lights were aimed directly at eye level to riders behind them. For group rides I'll usually set the Hotshot to steady and dim it a bit, although I think I forgot to do so last week. I'm guessing my flasher was acceptable aimed downward because our sweep or tailgunner will usually fuss at me to remind me to reset my taillight.
Our casual group is pretty loosey goosey about this stuff, but another faster group I sometimes ride with will fuss at and ostracize cyclists who aim their laser blinkies directly at eye level. They insist on steady lights only, aimed downward a bit, at least while riding with the group. Makes sense in winter when group rides are often in darkness, morning or evening.
However if you don't participate in nighttime group rides or commute on a busy MUP it might not be an issue. If I mostly rode busy streets and rural highways in daytime I'd get the brightest Hotshot and aim it level and directly back. In daylight it will appear piercing only to anyone directly behind you. The Hotshot has a very narrow aperture of intense brightness. This should help nudge any driver tailgating you off your tail. When I've been riding my bike and had to follow another cyclist using a bright Hotshot, all I needed to do was move to the side about a foot and the intensity decreased to a tolerable level.