• I use FreeCAD and OpenSCAD when you can write code instead of draw.
• Hardware design software is complicated because of hardware patents. For simulation there is Octave, scilab, sympy, einsteinpy and other python projects.
• For video there is openshot.
• For audio production there is Sonic Pi, strudel, where you write music by writing code. There is also audacity and fluidsynth. The problem is with VST plugins but it's also problem of standard because VST was created by Steinberg. There is no single software so you need to juggle.
• For office there are alternatives like OnlyOffice and fork Euro Office, I've seen at least one more office packet from India.

Opensource software have no budget and no money, not to mention marketing budget, people make it to use it and share not to sell it. When company dies you end up with no software if it's cloud based or some installer on deprecated operating system. With opensource you can always take the source code and port it to new OS. One opensource project dies, some other is building on it's ashes. You can't kill it as long as at least one person use it and develops it.

For ex. elastive wave mode solver if you mean dispersion calculator you can load matlab files to Gnu Octave or look up some specific waves by typing above projects I mentioned with github in search.

Of course it's much harder than just type to google what you want and pay money to company that have marketing division and worked out SEO to be first on list. Especially if you have business income that backs it up and limited time, just pay to get it done. It's obvious choice. I assume people are sane. But you can pretty much find all the scientific equivalents on univeristy websites or on github if you really put some effort. It won't be perfect because there was no support that someone paid to solve specific business use case but if you contribute to opensource it will improve and if not you over time someone will do it.

Like someone mentioned the process is much slower but eventually it will always win because it's not so much tied to money.