Some of them fought to prevent us to have what we have today. Many fought for bad causes, many fought essentially for nothing or because things were shit for no gain. There were two sides to every war. Many fought over which autoritarian will controll that village.
There is not reason to struggle unless you really struggle, through learning is good.
"Millions have died in wars for us to have what we have today"
is problematic. I think a lot of the replies interpret it as a case of this: https://en.wikipedia.org/wiki/Post_hoc_ergo_propter_hoc
Even if that's not what you are thinking: sure, people die fighting for particular causes, but people also die fighting to oppose those causes. The history of war doesn't confer any intrinsic moral value on fighting. What about https://en.wikipedia.org/wiki/Is–ought_problem
"There has been a ton of conflict and struggle for our species"
This is more ambiguous. What does the "for" mean? Could it be replaced with "in"? (i.e. it has just been endured) Or do you mean that the conflict and struggle has all been directed towards the furtherance of the species? (e.g. "it's been a tough two millennia for our species")
This is not simple stuff from a philosophical perspective.
a) There has been a lot of progress over the millennia (in many ways, from higher life expectancy to less violence)
b) Many people have sacrificed a lot to bring that progress about
c) We ought to be grateful and c2) struggle on.
I think a), b), and c) are uncontroversial, c2) needs to be argued for.
https://www.psychologytoday.com/us/blog/meditation-modern-li...
I don't think it's a good idea to take Psychology Today or any other pop psychology writing too seriously. Science doesn't have the answers yet in this area.
Related point is that it matters what one works hard towards and why, not just that one do.
What we have is going to vary from person to person. I have no thanks to all those people for giving me a life filled with discontent and conflict.