Editor has requested major revisions to manuscript. Should I give up? Three months ago, I submitted a manuscript to one of the most respected journals in my field. Today, I received comments from reviewers stating that my paper is not worth publishing in the journal. However, the editor decided to give it a major revision instead of outright rejection. Should I proceed to address all the questions posed by reviewers or should I just withdraw the paper and submit it elsewhere to save time?

EDIT:
Right now it seems impossible for me to pull off some of the outrageous suggestions from reviewers. They asked me to prove my theory by applying more expensive method that unfortunately cannot be afforded by my supervisor as her grant has already ran out and we lack of funding now. Another reviewer also ridiculed my experimental method and claimed that my method had lots of flaws.
Based on the description, I would advise you to sleep on it, suck it up, respond to the reviewers, revise the paper, and submit your revision to the journal.

Yes, reviewers can be absolutely, disgustingly, and unnecessarily rude and mean. Read their review, filter their non-technical rants, keep whatever helpful criticism you can extract from their comments, and address them nicely and respectfully. It may actually be that the techniques you used were adequate but you failed to point out why and how it would be unnecessary to use more expensive methods. Always assume that they are right. If they are mistaken, respectfully point out in your response why you are right and edit the original manuscript to make the issue clearer to future readers.

For instance, if the reviewer wrote:


  The methods used in the paper are abysmal. The authors use an outdated
  and archaic method, which is also very uncertain, to measure the mass
  of the frogs, which is by weighting them on a scale. The atomic mass
  interferometer, which uses gravitational waves and is able to
  precisely infer mass with an uncertainty of one atomic mass unit per kilogram,
  is the state of the art in weighting.


You can write as a response:


  The reviewer is absolutely correct that atomic mass interferometry
  (AMI) is the state of the art in weighting. However, we opted to use
  analytical scales to measure the mass of the frogs because the mass
  variations that we expected to measure are of at least 1 g, a quantity
  signficantly higher than the uncertainty of even the most rudimentary
  analytical scales. We do, however, agree, that the quantum mechanical
  analysis of the molecular buildup in neural entangled channels in
  during frog electrophoresis, which is suggested as an interesting
  prospective investigation, will benefit from the low uncertainty
  provided by AMI.
  
  In order to make it clear that the methods used in our study were
  adequate, we have modified the original manuscript to include the
  following sentence in the second paragraph of page 5:
  
  While there are more precise methods to infer mass, such as atomic
  mass interferometry, analytical scales offer accuracies that are
  compatible with the 1 g mass variations that were found in this study
  (see Table 3, for instance).