It took me too long to realize that you are probably not talking about something traumatic happening in 2017, but rather about the fact that 2017 was 9 years ago.

However I looked up things that happened in 2017 and these are the things that seemed relevant to me by my arbitrary scale:

• start of Tronald Dumps first presidency including all the stupid shit he did during his first year like withdrawing from the paris climate agreement and UNESCO
• Kim Jong-uns half brother gets assasinated
• the world's first reflight of an orbital-class rocket
• the last person born in the 19th century dies
• The first observation of a collision of two neutron stars. Both gravitational and electromagnetic waves from the event are detected.
• In the first month of the second phase of the Rohingya genocide starting in August 2017, at least 6700 people are murdered by the Myanmar military.¹
• The Treaty on the Prohibition of Nuclear Weapons is voted for by 122 states.
• Cassini–Huygens ends its 13-year mission by plunging into Saturn, becoming the first spacecraft to enter the planet's atmosphere.
• Fortnite releases 💀
• Based on the results of a previously held referendum, Catalonia declares independence from Spain, however no one cares², so Catalonia still part of Spain today
• A new species of Orang Utan is identified
• The Zimbabwean Military takes control of the country in a coup d'état
• ʻOumuamua is the first confirmed interstellar object detected passing through the Solar System

¹ the whole genocide has way more deaths (at least 24000), is still ongoing and caused 1,5 Million to flee the country

² it didn't receive recognition from any country and it produced no legal effect.