Personally I don't fit well into either trend: I was active in 2008, but the debate in this election feels significantly more bitter and aggressive. In part, this is probably because the stakes are a bit higher for the left this time: Sanders is significantly further to the left than either of the 2008 candidates, and the attacks on him have taken on a distinctly anticommunist tenor. But I think there's another difference between the two elections that's worth some reflection.
In 2008, I was utterly immersed in Team Obama. At the time, everyone in my professional and activist circles simply took for granted that Hillary Clinton was an unacceptable candidate who needed to be opposed at all costs. We were under no illusions about Obama, but he still seemed the clearly preferable choice; for us, the only real alternative on the table was either voting for Nader or staying at home.
Given this degree of consensus and solidarity, most of us could only look on the controversies of 2008 with incredulity and amusement. When Rebecca Traister rolled out a Salon piece decrying the sexism of Obama Bros, everyone instantly recognized it as the implausible and overtly partisan rhetoric that it was. When Clinton supporters gloated over victories in Michigan and Florida, we shrugged it off because we knew that it was empty bluster. When they hyped secret Michelle Obama "whitey" tapes that would soon come to light and derail her husband's campaign, no one was rattled; too many of us appreciated how absurd the allegation was, and that kept the rest from getting gaslit.
Obviously a lot of this confidence ultimately came from winning. We knew how weak Clinton's attacks were, we got that they were coming from a place of desperation, and we understood that overcoming them was largely just a matter of waiting out the clock.
But when I think about what made the difference personally, I think of solidarity. I remember being able to criticize Clinton on Iraq or welfare knowing perfectly well that her partisans would call me a sexist - and knowing perfectly well that no one would buy it. I remember openly ridiculing the PUMAs knowing that everyone was in on the joke, and that the sort of people who got upset about it weren't worth paying attention to. I knew that I could joke about Clinton pretending that she had dodged sniper fire in Bosnia - and that anyone who had a problem with that would get laughed out of the room.
This year I'm in a similar situation - but my impression is that things are quite different for a lot of Sanders supporters. I think that a lot of people on the left feel relatively isolated, and that the networks of social support and solidarity are a lot less secure. This has left people feeling insecure in their politics, less willing to speak out, and less confident when they're attacked. At the very least this kind of siege mentality makes the election a lot less fun; but at worst, it becomes exhausting and emotionally draining, an endless exercise in combative interpersonal diplomacy and defensive damage control.
My advice to the left, and to Sanders supporters in particular, is solidarity. Encourage each other when you're on the offensive; support each other when you're getting attacked. Never forget that the right's most powerful weapons have always been isolation and discord: they will try to marginalize you and to turn you against each other. Remember that you are part of a broad and deep historical movement, and that in most of the world people with your politics are the rule, not the exception. Be courageous in your opposition, have fun with it, and for those who are mostly active on the internet, always remember: it's just the internet.