Ben Horowitz, a venture capitalist, has attributed a quote to Karl Marx on several occasions.
On his blog in 2012:
Life is struggle. —Karl Marx
In a 2013 tweet.
In his 2014 book, The Hard Thing About Hard Things, (p. 274):
On my grandfather’s tombstone, you will find his favorite Marx quote: “Life is struggle.”
I had directed the mason to inscribe it with the words "Life Is Struggle," a favorite quote from his mentor, Karl Marx.
However, John Patrick Leary in "The Poverty of Entrepreneurship: The Silicon Valley Theory of History", is critical of Horowitz and claims it is a misquote:
One chapter epigraph, “Life is struggle,” is misattributed to Karl Marx.
I would be curious to know if Karl Marx ever said or wrote this.