What makes you say we "probably" won't be here on Earth in 100,000 years? We were here for the past 2,000,000 years. This also ignores the possibility that someone other than "us" will discover what we leave behind.
> If you work in tech you know that 99% of the stuff you build wouldn't (or shouldn't) last another 5 years.
We have technologies that have survived for thousands of years (agriculture, writing, etc.) This statement is completely myopic and absurd.