Elon Musk has publicly expressed strong support for Republicans and concern about Democrats winning midterm elections, but there is no verified record of him posting that 'no one has to worry about the Democrats winning the midterm election.'
Elon musk posted on Twitter no one has to worry about the democrats winning the midterm election

Musk Has Gone Quiet About the Launch of His 'America Party' — Here's What We Know - The Gateway Pundit | by Joe Saunders, The Western Journal
Source: thegatewaypundit.com
Key Evidence
Elon Musk urged Americans to vote Republican in midterms to counterbalance Democrats.
reuters.comreuters.comTwitter owner Musk backs Republicans on eve of U.S. midterms
He has expressed real threats if Democrats regain control, indicating concern rather than reassurance.
thegatewaypundit.comthegatewaypundit.comMusk Has Gone Quiet About the Launch of His 'America Party' — Here's What We...
No sources confirm a tweet or post from Musk stating that no one should worry about Democrats winning.
ap.orgap.orgElon Musk has often inflamed politically tense moments, raising worries for the...
cnn.comcnn.comElon Musk just made his starkest political threat since the election+1 more
What the Evidence Shows
Elon Musk has been an active and vocal figure in U.S. Political discourse, particularly around midterm elections, often urging voters to support Republican candidates to counterbalance Democratic control.reuters.comreuters.comTwitter owner Musk backs Republicans on eve of U.S. midterms
time.comtime.comHow Musk's Call To Voters Could Impact U.S. Midterm Elections
His public statements and tweets have frequently conveyed concern or alarm about the potential consequences if Democrats regain power, suggesting he views their victory as a threat to his interests and political goals.thegatewaypundit.comthegatewaypundit.comMusk Has Gone Quiet About the Launch of His 'America Party' — Here's What We...
en.wikipedia.orgen.wikipedia.orgViews of Elon Musk
There is no credible evidence from the provided sources or recent news that Musk posted a message reassuring people that "no one has to worry about the Democrats winning the midterm election." Instead, his messaging tends to emphasize the opposite, that Democrats winning would be problematic.
Musk’s political involvement also includes threats to introduce third-party candidates, which some analysts believe could split conservative votes and inadvertently aid Democrats.politico.compolitico.comElon Musk is threatening to put third-party candidates on the ballot. Democrats...
Given this context, a claim that Musk posted a message downplaying concerns about Democrats winning is misleading because it contradicts his known public stance and documented tweets.
In summary, while Musk is politically active and vocal on Twitter regarding midterms, the specific claim that he posted reassuring people not to worry about Democrats winning is not supported by available evidence and runs counter to his typical messaging.