I disagree. If anything Spidey is one of only 5 financially viable solo superhero franchises right now (CA, Thor, Batman and IronMan being the other 4).
He is only one of 4 solo franchises to break 700 million WW which makes him one of just 4 top-tier superhero film franchises.
The lesson to be learned with TASM2 is bigger budgets don't guarantee quality and may cause producers and others to get sloppy. When you have to pinch pennies there is much less temptation to waster money. If Cap 2 can be made for 175 million a Spiderman film can surely be made for 200 million.
Then of course the marketing. Again, less is more. Targeted marketing with a smaller budget forces effciences. Thor's marketing budget was far les than TASM2 but arguably more effective.
Spiderman remains, once again, just one of 5 viable franchises but SONY has gotten lazy in managing its resources. If TASM2 had cost 200 million and the marketing budget been tens of millions less the 700 million BO would be looking quite good right now.