How to create bookmarks in adobe acrobat reader dc

This is a GREAT workaround. Thanks.

I don't care if this is not the literally "correct" answer, it's the BEST answer because it solves my problem instead of simply telling me to spend the bucks on Pro or search for another PDF tool.

Yes this is possible using javascript supplied by pdfhacks.com.
I know this is responding to a very old post but as it was marked as the correct answer it is the most relevant place to put it. 
You can either download the needed file from here:  http://www.pdfhacks.com/bookmark_page/
Or alternatively open notepad, add the following script and save as bookmark_page.js in the folder named 'Javascripts' in the Acrobat Reader DC installation folder.
Instructions for use:

// bookmark_page.js, ver. 1.0
// visit: www.pdfhacks.com/bookmark_page/

// use this delimiter for serializing our array
var bp_delim= '%#%#';

function SaveData( data ) {
  // data is an array of arrays that needs
  // to be serialized and stored into a persistent
  // global string
  var ds= '';
  for( ii= 0; ii< data.length; ++ii ) {
    for( jj= 0; jj< 3; ++jj ) {
      if( ii!= 0 || jj!= 0 )
        ds+= bp_delim;
      ds+= data[ii][jj];
    }
  }
  global.pdf_hacks_js_bookmarks= ds;
  global.setPersistent( "pdf_hacks_js_bookmarks", true );
}

function GetData() {
  // reverse of SaveData; return an array of arrays
  if( global.pdf_hacks_js_bookmarks== null ) {
    return new Array(0);
  }

  var flat= global.pdf_hacks_js_bookmarks.split( bp_delim );
  var data= new Array();
  for( ii= 0; ii< flat.length; ) {
    var record= new Array();
    for( jj= 0; jj< 3 && ii< flat.length; ++ii, ++jj ) {
      record.push( flat[ii] );
    }
    if( record.length== 3 ) {
      data.push( record );
    }
  }
  return data;
}

function AddBookmark() {
  // query the user for a name, and then combine it with
  // the current PDF page to create a record; store this record
  var label= 
    app.response( "Bookmark Name:",
                  "Bookmark Name",
                  "",
                  false );
  if( label!= null ) {
    var record= new Array(3);
    record[0]= label;
    record[1]= this.path;
    record[2]= this.pageNum;

    data= GetData();
    data.push( record );
    SaveData( data );
  }
}

function ShowBookmarks() {
  // show a pop-up menu; this seems to only work when
  // a PDF is alreay in the viewer;
  var data= GetData();
  var items= '';
  for( ii= 0; ii< data.length; ++ii ) {
    if( ii!= 0 )
      items+= ', ';
    items+= '"'+ ii+ ': '+ data[ii][0]+ '"';
  }
  // assemble the command and the execute it with eval()
  var command= 'app.popUpMenu( '+ items+ ' );';
  var selection= eval( command );
  if( selection== null ) {
    return; // exit
  }

  // the user made a selection; parse out its index and use it
  // to access the bookmark record
  var index= 0;
  // toString() converts the String object to a string literal
  // eval() converts the string literal to a number
  index= eval( selection.substring( 0, selection.indexOf(':') ).toString() );
  if( index< data.length ) {
    try {
      // the document must be 'disclosed' for us to have any access
      // to its properties, so we use these FirstPage NextPage calls
      //
      app.openDoc( data[index][1] );
      app.execMenuItem( "FirstPage" );
      for( ii= 0; ii< data[index][2]; ++ii ) {
        app.execMenuItem( "NextPage" );
      }
    }
    catch( ee ) {
      var response= 
        app.alert("Error trying to open the requested document.\nShould I remove this bookmark?", 2, 2);
      if( response== 4 && index< data.length ) {
        data.splice( index, 1 );
        SaveData( data );
      }
    }
  }
}

function DropBookmark() {
  // modelled after ShowBookmarks()
  var data= GetData();
  var items= '';
  for( ii= 0; ii< data.length; ++ii ) {
    if( ii!= 0 )
      items+= ', ';
    items+= '"'+ ii+ ': '+ data[ii][0]+ '"';
  }
  var command= 'app.popUpMenu( '+ items+ ' );';
  var selection= eval( command );
  if( selection== null ) {
    return; // exit
  }

  var index= 0;
  index= eval( selection.substring( 0, selection.indexOf(':') ).toString() );
  if( index< data.length ) {
    data.splice( index, 1 );
    SaveData( data );
  }
}

function ClearBookmarks() {
  if( app.alert("Are you sure you want to erase all bookmarks?", 2, 2 )== 4 ) {
    SaveData( new Array(0) );
  }
}

app.addMenuItem( {
cName: "-",              // menu divider
cParent: "View",         // append to the View menu
cExec: "void(0);" } );

app.addMenuItem( {
cName: "Bookmark This Page &5",
cParent: "View",
cExec: "AddBookmark();",
cEnable: "event.rc= (event.target != null);" } );

app.addMenuItem( {
cName: "Go To Bookmark &6",
cParent: "View",
cExec: "ShowBookmarks();",
cEnable: "event.rc= (event.target != null);" } );

app.addMenuItem( {
cName: "Remove a Bookmark",
cParent: "View",
cExec: "DropBookmark();",
cEnable: "event.rc= (event.target != null);" } );

app.addMenuItem( {
cName: "Clear Bookmarks",
cParent: "View",
cExec: "ClearBookmarks();",
cEnable: "event.rc= true;" } );