Reset iMac main User Account? Multiple browser issues don't occur in Guest Account

The next step I'd try is to disable all items in the System/Login Item & Extensions/Open at Login settings pane. Then reboot and if it's fixed add one item back in at a time to find which item is the culprit.

Please download and run Etrecheck.  The free version is sufficient.

Copy the report as shown in this animated screenshot

and use the Additional Text button to paste the report in your reply.

Then we can examine the report and see if we can determine the cause of the problem.

After doing a quick review of the EtreCheck report two things stand out:

1. Configuration Files: File /etc/launchd.conf exists but not expected - This file exists either because a third-party app added it, it was caused by malware, or it is something you did and are aware of.
2. Numerous application crashes. with three apps/process crashing more than 25x within the last 60 days.

Those three apps/process are:

• gaileod (50x): The executable is located in /usr/local/bin/, which means it's not part of macOS itself but rather a manually installed or third-party application. The name "galileod" suggests it could be related to scientific computing, GPS services, or astronomy software. The -d at the end of the name typically indicates a daemon (background service).
  • Potential reasons why it may be crashing:
    • Binary Corruption or Incompatibility. This would be typical if the app was compiled for an older version of macOS.
    • If galileod relies on third-party libraries (e.g., Homebrew, Python, or ROS dependencies) that are missing or broken, it may crash immediately.
    • If galileod doesn’t have execute permissions or lacks access to required system files.
• axassetsd (52x): axassetsd is a system process related to Accessibility assets on macOS. It resides in: /System/Library/PrivateFrameworks/AXAssetLoader.framework/Support/axassetsd
  • It is part of a private Apple framework (not user-installed software).
  • It likely manages or loads accessibility-related resources such as VoiceOver, Magnifier, or Switch Control.
  • A persistent crash (52 times) suggests an underlying issue with accessibility services, system corruption, or a misbehaving third-party accessibility tool.
• MacinTalkAUSP (26x): MacinTalkAUSP is part of MacinTalk, Apple’s text-to-speech (TTS) engine. The AUSP part likely stands for Apple Unified Speech Processing.
  • The executable is in: /System/Library/PrivateFrameworks/MacinTalk.framework/Versions/A/PlugIns/MacinTalkAUSP.appex/Contents/MacOS/MacinTalkAUSP
  • Since it is a system-level app, the crash is likely due to a problem with macOS’s speech synthesis engine.
  • This could affect VoiceOver, Siri, Dictation, or any app using system speech (like Messages, Safari’s "Read Aloud", or accessibility tools).

Since you verified that this still occurs in Safe Mode with your existing user account, pretty much means that account would need some serious troubleshooting to figure out how to salvage it. At this point, I'm not sure it will be worth the effort and would only suggest that you re-install macOS.

The Abort trap: 6 specifically refers to an assertion failure in macOS, which often occurs when a program encounters an internal inconsistency or illegal operation that forces it to crash.

Some potential causes are:

• The browser may be using an outdated or corrupted version of a library or plugin required by the financial website.
• Some security extensions or ad blockers may interfere with the website's security protocols. Are you using any third-party extension with all of your web browsers?
• If the browser is consuming too much memory, macOS may terminate it to prevent further instability.
• If the website or its certificate handling triggers macOS security mechanisms, the browser may be terminated to prevent potential security risks. However, if you are able to access these same sites with another user account then this would indicate an issue with your current account ... as you expected.
• Some financial institutions enforce strict security policies, and your browser may be attempting to use an outdated or unsupported protocol.

Which exact model is your iMac and what version of macOS is it currently running?

Did you try starting in safe mode?

There is no way to "reset" a user account. The best you can do is try to determine exactly what is causing the problem.

Start here: Clear the history, cache, and cookies from Safari on your iPhone, iPad, or iPod touch - Apple Support

❝ Clearing the Safari cookies and cache, but keep your history

1. Go to Settings > Apps > Safari > Advanced > Website Data.
2. Tap Remove All Website Data.

When there's no website data to clear, the button to clear it turns gray. The button might also be gray if you have web content restrictions set up under Content & Privacy Restrictions in Screen Time. ❞

Have you installed and run any "cleaning", "optimizing", "speed-up", anti-virus or VPN apps on your Mac?