if one blows then what.you going to reach for the other 3??
If one blows, anything nearby will be on fire. Having 4 chargers will make next to no difference unless they are in 4 separate fire proof rooms.
FWIW, I recently bought this on banggood for $54:
DJI Phantom 3 Battery And Transmitter Charger Plates 110-240V Input 4 In 1
Is it any good ? Who knows, so far it seems to work just fine, each battery lead is independently regulated and puts out very close to 17.4V. These chargers aren't even really chargers, they are just regulated power supplies, no different from the one in your 3D printer, computer, whatever. Just at an unusual voltage. Its not rocket science, and shouldnt cost an arm and a leg.
I will say EM shielding of the banggood charger is terrible, at least it utterly failed my AM radio test (turn on a AM radio nearby, then turn on the charger and listen for interference). The OEM charger also gives some interference, but not as bad.
Anyway, I try to charge on a concrete floor with as little flammable things nearby as possible with any lipo charger, certainly with this one. YMMV.