Not to mention Tobi is shifty, deceptive, clever, and kniving. Plus he's our main antagonist and has the Rinnegan. No reason to think that he DOESN'T have access to it.

we don't know if Tobi is Uchiha or not though, if you're assuming that Tobi is not an Uchiha.

Even though I was the one who had a 200+ word essay of the many reasons tobi could easily = obito with massive evidence.. I still feel the need to say this.
Obito's other eye was crushed by rocks
The fuck is this doing in my naruto universe?

I have a 1000+ words Thesis on why Tobi can be Obito XD

Thought the same thing LOL its why kalashi only has his left eye

If Obito's other eye got crushed by rocks than how did Tobi get that Kamui jutsu? This part I am confused with. Tobi even claimed that he took Obito's other eye but how can that be true? This whole story is confusing me or some reason.

obito's twin / dad/ sister/ etc

I think Kishi fucked up, bad story telling if its really Obito's eye.. but I would like to see my giant ass prediction come true (not him being obito so to speak, but how he became tobi)

tobi is danzo. The one sasuke killed was a clone made by zetzu.

it's yet clear if he's Obito or if he stole the eye.
for all we know Kishi will say something about, he used Obito's crushed eye and fused it with his blah blah blah.
It was definite that Obito's other eye got crushed but recent chapter suggest that it might have survived and is currently being use by Tobi.
Other theory is that Tobi sucked in Obito's dead body and keeping it semi alive and is using the eye's potential.