First of all his drop rate will be really really low, just like edo minato frags from event wheel of fortune, many players spent over 10 and 15k but did not got him.

And secondly, even if you get him for 200 coupons, no need to be happy that you got some good ninja(yeah you should be happy that you got one of the rare ninja but he * to use). And even if he gets some game breaking skill break in future, it will still cost 4*.

I wont suggest anyone wasting his coupons, trying to gamble for obito and then being sad one the end of day

haven't heard of any such math in past 3 years. If you are lucky you can get with 20 or 30 pulls only. Other wise you wont get him with even 1600 or 1700 coupons. All you will get is regrets