100-200 is pretty safe for me, I'll probably HODL them until the price runs upwards. Bitcoin will eventually stop producing blocks, so why not? I see a nice investment here, but there are 2 things that'll probably restrict me:
1. A really long time
2. Bitcoin could die in that time
3. Price might flop (but this is so far in the future, remember)
Only time will tell, but for now I'll be saving some cash from various places including my signature campaign, and hopefully I can hit it rich someday.
I definitely should have bought more bitcoin when the price was around 350$, but it's too late now. If you ever plan to timetravel, bring an antminer s9, a ethernet cable, and a PSU. Easy money
I imagine that the network would be disrupted, but just don't travel TOO far back :p