Well, the nuclear industry in France uses Salome/Code_Aster which is for free. It’s not like its not capable, but open source software is not always very easy to set up, not always the most friendly UI either, and it’s not integrated with the CAD tools you’d like to use. And one would have to import the CAD files and redo the pre-processing after every change.
Also, any FEA analysis needs pre-processing of the models as to simplify and/or cleanup detailed features like holes, fillets etc. Some software does that automatically, and others yet even record what was removed so as to be able to repeat the exact same cleaning process in the next round if the original model needs change, and so on.
But if those advanced preprocessing features is worth like 10.000 USD+ for most people is questionable. I will happily spend an hour, or ten, cleaning a model before analyzing it, no problem (well, probably like 90% or more of the world’s engineers - outside Europe and the USA and the rest of the West - actually do so, as we speak)
I know full well that basic commercial FEA packages (non-linear) cost like $10.000 and more depending on modules needed (Creo Simulation, for example). Frequency and Thermo analysis is usually separate modules, but the price says nothing about it’s capabilities compared to, well, other free software out there. It seems like its the integration of pre- and post process and user friendliness which is the biggest difference. And integration with the CAD software of preference, and in some cases windows versions are not available.
Also, some basic FEA analysis, if repeated by an amateur with combinations of set ups, would still indicate trends and which direction to go for more analysis, and so give basic hints about weak points in the design that can easily be reduced. After that one can let experts do final tests.
There’s a reason for why some CAD packages integrates simple FEA analyses (like Fusion 360) despite the level of skills need for high accuracy results.
Don’t scare people away from even trying (I’ve done way “too complex” things given my formal or even expected competence) . 
// Rolf