This is an adverb that expresses the speaker's feeling that no matter what he/she does, or how he/she does it, the situation will not change.
"... どうせ is used when the speaker has already decided what the outcome will likely be, and has a negative tone. This is one thing that makes どうせ different from 結局." -Harlequin
After all, the money you now have will be gone soon.
I know you won't help me. That's the kind of guy you are, after all.
I'm not complaining. I had to get some cleaning done at home anyway.
If do you it at all, try to do it well.
If you are going to study kanji at all, study properly everyday.
At any rate, if you learn English, study it enthusiastically.
Anyway, whatever I say, you are going to go、right.
*Note: I have also seen どうせ used with just a noun:
He's a man after all.
This is usually said when us guys do something manly (or in the eyes of women, stupid). Could that mean something similar to the sarcastic English comment above? Also, if さすが were to replace どうせ in the above example, wouldn't the nuance be similar?
"To me, さすが sounds clearly like praise. どうせ, at least to me, sounds like quite the opposite - either the speaker is giving up on him or demeaning him by his characteristically masculine traits." -Futureal
"No, さすが is generally a positive word, どうせ a negative. However さすが can be used ironically, but the statementsどうせ男だ and さすが男だ (even when used ironically) remain very different in meaning. " -Harlequin