It's amazing how much hubris it took to sink the Second Reich. As far as I can tell, Germany was on track to win the war as late as spring 1917. They had the resources and the right strategy: defensive in the West (retreat to the Hindenburg Line) and offensive in the East. The last crucial mistake was resuming unrestricted submarine warfare at the same time. This predictably drew the US into the war. By summer 1918, the benefits of defeating Russia and Romania in the East were nullified by American troops pouring in at a rate of 10,000 a day, and the war's outcome was pretty much sealed.
Even without US involvement, France, Britain, and Germany were effectively all devoid of manpower. Once the Spring Offensive failed, there really wasn't any ability on any side to carry on offensive operations, at least to the point of producing a clear end to the war. So the first country to fall apart from the stalemate would be the one to lose it all. And Germany certainly seems the strongest contender for being the first to fall. It was having problems keeping even its soldiers well-fed, and the Spring Offensive produced a very indefensible salient. Germany's hopes of victory died at the Second Battle of the Marne, and they probably would have died there even had the Americans not started streaming to the front lines.
Regarding 1918, the Germans were pushing so hard and getting stretched because the AEF was streaming in [1]. (American divisions were involved in plugging holes at the Second Marne BTW.) The Germans had a superiority of 300,000 men going into spring 1918, and inflicted 150,000 more casualties than they took during the Spring Offensive. Unlike 1914, there was no rush to beat the French before the Russians mobilized. If it wasn't for the US intervention, it would have been offensive after offensive until the Entente caved in.
Wilhelm II was even planning an invasion of America in the late 1800's/early 1900's, an attempt at gunboat diplomacy[1].
[1] https://www.theguardian.com/world/2002/may/09/kateconnolly
So did this fact provide the ground for the belief, which helped lay the groundwork for the success of the Nazi movement, that Germany had lost the war because it had been betrayed by its leadership?
[1] https://www.history.navy.mil/research/library/online-reading...
As an example, read Aethelric's post here as it is important in explaining the seeds that set Germany as it was in 1869.
https://www.reddit.com/r/AskHistorians/comments/1v3vk8/why_d...
The region we now know as Germany was a series of small towns with mostly independent rule. With instability (especially crumbling of the Austro-Hungarian Empire), Germany established formal alliances quickly as the political climate grew in intensity.
Franz Ferdinand was shot, the European states fought and the US (with late entry) injected fresh ideas, troops and supplies, which decisively turned the tides of a messy war.
So, 1869 was more like a traffic light that triggered the car crash. Without understanding the history, you can't really understand each participant's trajectories or motives. To limit the answer to "1869" is only slightly more informative than limiting the answer to "Arch Duke Franz Ferdinand's assassination".
First off, it's rather well-known that Germany's fear of a two-front war and encirclement led to much of its preliminary war plan. On the other hand, the circumstances that led up to such a scenario were not preordained from its construction. It was largely a result of the early 20th century Germany managing to piss off just about everybody else with amazingly inept foreign diplomacy. In particular, Germany decided to give up its relationship with Russia, which France eagerly took advantage of and bound the two countries fairly close together. Germany's naval race with Britain also did much to antagonize it for no real gain.
Also, Alsace-Lorraine is much oversold as a cause of war. It's true that France did want Alsace-Lorraine back. But many in France were not prepared to go to war to actually achieve that aim. Instead, the situation in France post-Franco-Prussian War was to try to find allies that could help divert German attention, and their allies were the Russians who needed lots of help to even minimally qualify for that role and the British who went to rather great lengths to try to avoid actually fulfilling their commitment when August 1914 came around (Germany marching through Belgium gave Britain the political cover to actually commit).
As for whether or not Germany could win, that's a difficult what-if to answer. The Schlieffen Plan was, in the abstract, a masterpiece of precision planning and timetabling. But the plan also had very little room for change if things didn't work out. Belgium put up an unexpectedly fierce resistance, Austria-Hungary had a surprisingly hard time in Serbia, and Russia was doing better at first than Germany expected. In the end, the German momentum and logistics chain was incapable of carrying them to Paris, which completely ruined their plans and any hope of a quick end to the war. And Germany was completely unprepared for that scenario (to be fair, no one else was).