The simple reason is that a lot of people feel that the status quo just isn't working for them and hasn't been for a number of years. So they've ended up gradually voting for more and more extremes as the years have gone by, to express their distaste.

Hopefully these results are a wake-up call for EU nations, so they can try and get these voters back to the more moderate parties. I suspect not though.

Results of bad management of 2015 immigration crisis, and populist manipulation during the COVID lockdown powered by russian propaganda and American talking points.

In short: situation crazy, people mad, current governments no handle good, people more mad, bad people take advantage

Here's my hot take: people aren't switching to far right parties all that much. In a moderately healthy democracy, up to 30% of voters are often protest voters. They are unsatisfied with the current state of affairs and vote for whoever promises the largest upset of the status quo that they could see as potentially benefitting them.

Often the media then likes to massively overinflate their popularity, artificially enhancing their electoral success. But it's also often short-lived. If you look at Dutch elections, you'll find that a group of voters went for LPF, then PVV, then FvD and then PVV again. Each time it's broadly talked about as the "rise of X party" but almost every time nothing truly materializes.

In the US you see a hardcore group of approx. 30% of voters vote for Trump religiously. Then there's a smaller group of moderate Republicans that dislike the Democrats enough to end up voting for Trump too. They don't like Trump but he's "ok enough, and better than Obama/Clinton/Biden/Sanders etc...".

In France, Le Pen got around 30% of the vote. She didn't perform dissimilarly to the last presidential election results, it was more noticeable that the other parties got much smaller than they were. But whether or not Le Pen can actually take the crown remains to be seen.

I've seen one take that (maybe over-) simplifies to that there's a wave of anti-establishmentalism, and while the best party to embody that under FPTP (e.g. UK, USA) is the other big party, many European parliamentary systems have proportional voting systems that allow smaller alternative parties. And the alt right sells a load of coherent, anti-establishmentalist talking points.

Dutch examples: PVV? The problem is Islamic immigrants. FvD? The problem is the Deep State^TM^!

And although a lot of problems that we are experiencing (skyrocketing housing prices & cost of living, worsening labour conditions, millennials and gen Z/Alpha being worse off than their parents) are the result of the right, the left does not have a thing to sell as easily as the alt right has been able to.

I said in another comment but basically the left have a tougher message to sell than the right. The right says that the system works but it's the foreigners/benefit thieves/refugees stealing your money/house/jobs. That is inherently quite easy to understand without much thought or critical thinking. The left on the other hand have to tell you all about Thatcher, Reagan and neoliberalism before we even get to the point of solutions which are usually incredibly radical like changing the fundamental economic model we've all been operating under since the 80s. Inherent in that is a fear that the left's solutions will take assets and wealth away from people. While the right promises that your assets, wealth and property rights are sacred and that it's the "other" that will have their assets, wealth and rights taken away. Again, very easy-to-understand messaging for the right versus the left.