Has anyone won all three Grand Tours?
The short answer is no. The longer answer is sorta. And the longer answer is sorta and probably never again.
What is a Grand Tour?
As a reminder a Grand Tour is one of the three major three week cycling events that span the calendar year. These are, in order of start date, the Giro, the Tour de France, and La Vuelta.
Why is the short answer no?
Generally the question is framed around if a rider has ever won all three Grand Tours in the same calendar year. In that regard there has never been a rider to do so.
Why is the long answer sorta?
There have been riders who have won all three in succession, hence holding all at once, but having spanned this feat across calendar years. So for example they won the Tour de France in 2022, La Vuelta in 2022, and the Giro in 2023. There are three of these riders: Eddy Merckx, Bernard Hinault and Chris Froome.
Why is the longer answer never again?
In the era of modern cycling each race is raced incredibly hard. Riders can no longer use early season races as training, altitude camps are a must, and riders must "peak" their performance for each of the events they want to perform well at. The pointy end is now so high, and high across the board (as in there's no longer just one team, eg. a Team Sky that has all the best knowledge or talent) that domination by one rider or one team for all three events seems increasingly out or reach.
If a rider wanted to attempt to achieve the feat they'd miss out on altitude camps, rest and recovery, or more productive training (Grand Tour "racing" days aren't that productive for top GC contenders). This would limit their ability to peak and win against their comptetition who had been planning and peaking for the event. And boy is their competition these days.
Don't get us wrong! We'd love to see it happen. We just don't think it will. Despite how good a Pogačar or Evenepoel is.