To estimate as insignificant or worthless... this is an opportunity for you to use (perhaps) the longest word in English:
It's an opportunity not to be floccinaucinihilipilificated, that is you should consider it seriously.
Ok, well that was a bit of a joke answer, floccinaucinihilipilification isn't a "real" word, as it was made up as a very long word. For a real answer, I would use "scoffed". To "scoff" is to speak or laugh about something in a derisive or mocking manner. The idiom "not to be scoffed at" means "to be taken seriously.
This is an opportunity not to be scoffed at; you should take it seriously.